Imam A'li (A.S.) said to Ibn A'bbas:
(Once when he happened to pass by Kerbala), Isa (A.S.) sat down and began to weep. His disciples who were observing him, followed suit and began weeping too, but not comprehending the reason for this behaviour, they asked him: "O' Spirit of God! What is it that makes you weep?" Isa (A.S.) said: "Do you know what land this is?" The disciples replied: "No." He then said: "This is the land on, which the son of the Prophet Ahmad (S.A.W.) shall be killed.
Bihar al Anwar vol 44 pg. 252.