مُسْنَدُ أَحْمَدَ
Musnad Ahmad 2049
Musnad of 'Abdullah bin al-'Abbas bin 'Abdul-Muttalib from the Prophet
It was narrated that Ibn ‘Abbas said: I heard the Messenger of Allah (ﷺ) say: “There are three things that are obligatory for me and are voluntary for you: Witr prayer, offering sacrifice and Duha prayer."
Musnad Ahmad 2050lts isnad is da’eef. Abu Janab al-Kalbi is da'eef]