مُسْنَدُ أَحْمَدَ
Musnad Ahmad 2079
Musnad of 'Abdullah bin al-'Abbas bin 'Abdul-Muttalib from the Prophet
It was narrated that Ibn 'Abbas said: The Messenger of Allah (ﷺ) said: "I have been commanded to pray Duha and Witr, but it is not obligatory [for you].”
Musnad Ahmad 2081lts isnad is da'eef because of the weakness of Jabir al-Ju'f