There is a difference of opinion among the Shi'āh and Sunni Scholars, traditionists and historians regarding the day, month and year of the birth of Imām Husayn (a.s.). Some opine that he was born on the third of the month of Sha'bān or fifth of the same month, or on the fifth of the month of Jamādi' ul Ulā forth year after Migration (Hijrāh), while some say that it was in the end of the month of Rabi' ul Ulā third year after Migration.
Thus, Shaikh Al-Tusi in his Tahzeeb, Shaikh Shaheed al Awwal in his Duroos, and Shaikh Bahāi in his Tawzeehal Maqāsid unanimously agree and accept the tradition of Siqatul Islām (the Trustworthy Authority of Islām) Shaikh Kulaini (May Allāh sanctify his grave), that Imām Ja'far as Sādiq (a.s.) said that,
“The distance between (the birth of) Imām Hasan (a.s.) and (the conception of) Imām Husayn (a.s.) was a Tuhr (a period of cleanliness between two consecutive menses), while between their birth six months and ten days.”
What is meant here is the minimum period of cleanliness, which is of ten days. Imām Hasan (a.s.) was born on the fifteenth of the month of Ramazān in the year of the battle of Badr i.e. second year of Migration (Hijrāh).
Besides, it is related that the distance between (the birth of) Imām Hasan (a.s.) and (the conception of) Imām Husayn (a.s.) was not a period of a Tuhr (cleanliness), and Imām Husayn (a.s.) remained in his mother's womb for six months.
It is written in the Manāqib of Ibn Shahr Āshob from Kitāb al Anwār , that Allāh, the Exalted, sent felicitations to His Prophet Muhammad (S) regarding the conception and birth of Imām Husayn (a.s.) while condoling him for his martyrdom. When Hazrat Fatima az Zahrā (a.s.) was informed about it, she was grieved, then the following verse was revealed,
“With trouble did his mother bear him and with trouble did she bring him forth, and the bearing and the weaning of him was thirty months”. (Sura al Ahqāf, 46:15).
Shaikh Saduq, through his chain of transmitters, quotes from Safiyyah bint Abdul Muttalib, that she said: When Imām Husayn (a.s.) was born, I was attending to his mother. The Holy Prophet (S) came to me and said,
“O Aunt! Bring my son to me.”
I replied that I had not yet purified him. He replied,
“Will you purify him? Rather Allāh, the Exalted, has cleansed and purified him.”
In another tradition it is related that Safiyyah says that she then gave the child to the Prophet who placed his tongue in his mouth, and Imām Husayn (a.s.) started licking it. Safiyyah says that I strongly perceive that the Prophet did not give him anything else except milk and honey. She says that then the child urinated and the Prophet planted a kiss in the centre of his eyes and wept, then handing him over to me said,
“O my dear son! May Allāh curse the people who will kill you”,
and he repeated it thrice. I asked, “May my parents be your ransom! Who will kill him”? and he replied,“The oppressive group to emerge from among the Bani Umayyāh.”
It is related that the Prophet recited the Azān in his right ear and Iqāmah in the left one. Imām Ali Zainul Ābedeen (a.s.) relates that the Holy Prophet himself recited the Azaan in the ears of Imām Husayn (a.s.) the day he was born. Besides it is related that on the seventh day the Aqiqā was performed and two white charming sheep were sacrificed, one thigh of which along with a gold Ashrafi (a gold coin) was given to the mid-wife. The hair of the child was shaven off and silver equal to it's weight was given as charity, then scent was applied on the child's head.
The Trustworthy Authority of Islām Shaikh Kulaini relates that Imām Husayn (a.s.) did not drink milk from his mother Hazrat Fatima (a.s.) nor any other woman. He was always brought to the presence of the Holy Prophet who gave him his thumb to suck. Imām Husayn (a.s.) sucked his thumb and then would remain satiated for two or three days. Thus Imām Husayn (a.s.)'s flesh and blood was formed from the flesh and blood of the Holy Prophet (S).
Shaikh Saduq (May Allāh sanctify his grave) quotes Imām Ja'far as Sādiq (a.s.) as saying that when Imām Husayn (a.s.) was born, Allāh commanded Jibra'eel to descend upon the earth with a thousand Angels and congratulate the Prophet on His behalf and himself. Jibra'eel descended and on the way he passed by an island where an Angel named Fitrus, who was a bearer of the empyrean, lay there banished.
Allāh had once assigned a job to Fitrus who delayed it due to laziness; hence Allāh took away his wings and expelled him to the island. Fitrus worshipped Allāh there for seven hundred years until the time Imām Husayn (a.s.) was born. When Fitrus saw Jibra'eel he inquired of him as to where was he going. Jibra'eel answered that, “Allāh, the Exalted, has bestowed His Blessings (Imām Husayn) upon Muhammad (S), thus Allāh has commanded me to go and congratulate him on His behalf and myself.” Fitrus said,
“Then O Jibra'eel! Take me too along with you to the presence of the Prophet, perhaps he might pray for me.”
Jibra'eel lifted him up and brought him to the Holy Prophet (S). When he reached there he offered condolence to him on behalf of Allāh and himself, then he presented the matter of Fitrus. The Prophet commanded Fitrus to touch himself with the body of Imām Husayn (a.s) and arise. Fitrus did so and ascended upwards saying,
“O Prophet of Allāh! This son of yours will be mercilessly killed by your nation. Therefore it is incumbent upon me in exchange of this favor that I recompense. Hence there is no person who visits his grave except that I receive him, and there is no Muslim who offers salutations to him or who prays for him except that I take it to his presence and carry his message.”
Saying this Fitrus flew away. In another narrative it is related that Fitrus flew away saying,
“Who is similar to me? For I am a freed one of Husayn (s.a.s), the son of Ali (a.s.) and Fatima (a.s.), whose Grandfather is Ahmad (S).”
Shaikh Al-Tusi relates in misbāh that Qāsim bin Abul Alā'a Hamadāni (the agent of Imām Ali an Naqi) received a written pronouncement from Imām al Mahdi (a.t.f.s.) which read as follows: Our Master Imām Husayn bin Ali (a.s.) was born on Thursday, the third of the month of Sha'bān, therefore fast on that day and recite this supplication: “O Allāh! I ask you in the name of the one who is born this day…(till the end)” Furthermore the following words are quoted: “Fitrus took shelter under his cradle, and we seek shelter after him under his grave.”
Sayyid ibn Tāwoos says in Malhoof that there was no Angel in the Heavens who did not turn up to congratulate the Prophet (S) on the birth of Imām Husayn (a.s.) and condole him for his martyrdom, and revealed the reward reserved for the Imām. They showed him the grave of Imām Husayn (a.s.), and the Prophet prayed,
 The author says that we strongly perceive that in reality the above verse refers to Imām Husayn (a.s.) and Prophet Yahyā (a.s.) (and not Prophet Isā) for their lives were quite identical to one another while the period of their mother’s pregnancy was the same. It is related that Prophet Yahyā (a.s.) remained in his mother’s womb for six months as Imām Husayn (a.s.), whereas in the case of Prophet Isā (a.s.), it is found in numerous traditions that his mother bore him for a very short period viz. nine hours, each hour equal to a month, and this seems quite acceptable. It is related that Ummul Fazl, the wife of Abbās bin Abdul Muttalib (the uncle of the Prophet) who nurtured Imām Husayn (a.s.), recited some couplets eulogizing him.
 Ibn Shahr Āshob writes in Manāqib that one day Jibra’eel descended and saw Hazrat Fatima (a.s.) sleeping while Imām Husayn (a.s.) was feeling restless and weeping. Jibra’eel sat down and consoled and played with the child until Hazrat Fatima (a.s.) awoke, and the Prophet apprised her of this. Sayyid Hāshim Husayn Bahrāni quotes in his Madinatul Ma’ājiz from Sharhabeel bin Abi Awf, that when Imām Husayn (a.s.) was born, an Angel from among the Angels of the High Paradise descended and went to the Great Sea and called out between the Heavens and the earth, “O servants of Allah! Wear the dress of grief and sorrow, and mourn, for the son of Muhammad (S) lies beheaded, oppressed and subdued.”