Another etiquette of prayer is that the supplicant should renounce sinning, especially transgressions, oppressions, and eating forbidden (haram) things. He should not raise his hand of oppression towards people's lives, possessions, and prestige, instead should endeavour to have a pleasing character. Following are some of the traditions in this regard.
In a divine tradition it has been narrated:
"From you is the prayer; and it is up to Me to grant it; the prayers of all supplicants are granted except those who have filled their bellies with food provided through forbidden (haram) means."
The Holy Prophet [s] has narrated:
"Whoever wishes his prayer be granted by Allah must endeavour to earn his sustenace through lawful means, i.e., he must restrain himself from earning his living through fraudulent and forbidden means."
Allah (the Glorious, the Exalted), has recommended to Prophet Jesus [a]:
"Say to the oppressors of bani-Israel: Do not beseech Me in the state of idol-worshipping and usury, because, I have sworn that whoever beseeches Me I will grant his needs, and My grant for those who are indulged in idol-worshipping and usury would be nothing except cursing and damnation for them."
It has been narrated from the Holy Prophet [s] that Allah (the Glorious, the Exalted), sent revelation to him:
"Warn the Islamic community (Ummah) not to congregate inside the mosque for offering prayer and beseeching Me while being transgressors or oppressors towards other human beings, in that case till they are busy in prayers and supplications would only be inflicted with My curse and damnation, or otherwise they must remove that transgression from themselves (through obtaining the consent of the oppressed). It is only after this stage that they will become nearer to me, so that I would become their eyes and ears, and would make them companions of the prophets, martyrs, and righteous saints."
About the non-acceptance of prayer of someone in bani-Israel it has been narrated that his prayer was not granted, because, he besought Allah (the Glorious, the Exalted), with a contaminated tongue and heart as well as with ill intention.
It has been narrated from the Holy Prophet [s]:
"That whoever beseeches Allah with immodest character is like someone who wants to shoot the arrows with a chord-less bow."
Imam al-Sadiq [a] has said:
"Allah does not grant the prayer of a sleeping and negligent heart, therefore, one should pray to Him whole-heartedly, and should beseech him with attention while being fully awakened, only then a supplicant should look forward for his prayer being granted."
It has been mentioned in a tradition that the prayer of the following is not granted:
It has been narrated in a tradition that:
"Whoever prays against his neighbours and relatives, or asks forbidden things (haram) from Allah his prayers are not granted."
Also, it has been quoted from the Commander of the Faithful Imam 'Ali [a]:
"That while beseeching Allah one should not ask for impossible and forbidden things."