Tradition

The Messenger of Allah (s.a.w.a.) said: I will be at the Pool of Kawthar on the Day of Judgement and you, O Ali, will distribute the water. Hasan will keep people away from the Pool; Husain will give the orders; Ali bin Husain will be the enforcer; Mohammad bin Ali will be the revealer; Jaafar bin Mohammad will be the driver; Musa bin Jaafar will be counting the lovers and the resentful, and he will be the destroyer of the hypocrites; Ali bin Musa will beautify the believers; Mohammad bin Ali will award degrees to the inhabitants of Paradise; Ali bin Mohammad will be the preacher of his Shia and he will marry them from Hur al-een, “Pure maidens with big beautiful eyes” (Surah Waaqiyyah (56):22); Hasan bin Ali will be the light of the inhabitants of Paradise – they will see with his light; and the Qaem (12th Imam) will be the intercessor who will ask Allah to allow them (the believers) to enter Paradise on the Day of Judgement, a day on which Allah will accept only the intercession of those with whom He is pleased.
Faraaed al-Simtain v 2 p 231 Maqtal al-Husain v 1 p 94 Behaar al-Anwaar v 36 p 270 Ghaayah al-Maraam p 35