When Imam Hasan (peace be upon him) was about to die, those around him observed that he (peace be upon him) was weeping and so they asked: O’ Son of the Prophet of God! Despite your relationship with the Holy Prophet (peace be upon him and his holy progeny) and the rank and status that the Holy Prophet (peace be upon him and his holy progeny) has mentioned about you do you still weep? Twenty times you have performed Hajj on foot; on three occasions you have given one half of all your wealth in the way of God, and yet you weep?
The Imam (peace be upon him) said: I weep due to fear of Qiyaamah and separation from my friends.( Pand-e-Taareekh, vol. 4, pg. 208. )