Sunan Abi Dawud Book 5, Hadith 51
The Prophet (ﷺ) came to the mosque of Banu AbdulAshhal. He prayed the sunset prayer there. When they finished the prayer, he saw them praying the supererogatory prayer after it. He said: This is the prayer to be offered in the houses.
That an al-Ansari narrated to him: The Messenger of Allah (ﷺ) said to Ja'far. He then narrated the tradition in like manner. This version has the words: "In the second prostration of the first rak'ah" in addition to the words transmitted by Mahdi b. Maimun (in the previous tradition).
The Messenger of Allah (ﷺ) used to prolong the recitation of the Qur'an in the two rak'ahs after the sunset prayer until the people praying in the mosque dispersed.
Abu Dawud said: This has been reported by Nasr al-Mujaddir from Ya'qub al-Qummi with the same chain of narrators.
Abu Dawud said: Muhammad b. 'Isa b. al-tabba' transmitted from Nasr al-Mujaddir from Ya'qub in like manner.