Hasan bin Hamza bin Abdillah narrated from Ahmad bin Al-Hasan Al-Khashab, from Ayyoub bin Nuh, from Abbas, from Amr bin Aban, from Aban bin Taghlab, from ‘Ikrama, from Ibn Abbas, who said:
After returning from the farewell pilgrimage, the MESSENGER OF ALLAH (SWT) said:
O people! Jibraeel, the Honest Spirit, came to me from ALLAH (SWT), the Magnificent, and said, “O MOHAMMAD (SAWW), ALLAH (SWT) says that he misses seeing you. So prepare a good will and finish what you have to do.”
O people! My time has come (to an end) and I can see us leaving one another. So if your bodies have left me, do not allow your souls to do the same. O people! ALLAH (SWT) has never created an immortal PROPHET (SAWW), and I am not immortal. ALLAH (SWT) has said in this verse in the Qur'an,
“We have not granted to any man before you eternal life. What! if you die, will they live for ever? Every soul shall taste of death"(21:34-35).
Understand that my Lord has ordered me to leave a will for you. Understand that my Lord has ordered me to show you to the ark of rescue and the door of sustenance.
Those of you who want to survive after me and be safe from the destroying seductions should hold firmly to the Wilayat of ALI BIN ABI TALEB (ASWS). He is the most truthful and the best separator of right from wrong.
He is the Imam of every Muslim after me. Those who love him and follow him will be next to me by the Pool of Kawthar on the Day of Judgement. I will see those who disobey him on the Day of Judgement, but they will not see me. They will be pulled towards others who will take them deep into Hell.
Then the PROPHET (SAWW) said, “O people! I have given you the best advice but you do not like the advisors.I say this and I seek forgiveness for myself and for you.”
Then he held ALI (ASWS) ’s head and kissed his forehead.
Then the PROPHET (SAWW) said to ALI (ASWS) , “O ALI (ASWS) , your virtues cannot be counted. I swear to ALLAH (SWT), who created the seeds and created people, if all creatures would concede to loving you and understanding your true status, ALLAH (SWT) would not have created Hell.”
(Ref: Ghayatol Maram P45 H48. Ehqaq Al-Haq V4 P331)