Musnad Ahmad 1153:2040

Rawh narrated to us, he said: Ibn Jurayj narrated to us, he said: Ziyad informed me that Abu Nahik informed him that Abu al-Darda’ used to preach to the people that there is no Witr for one who reaches the morning. Some men of the believers went to Aisha and informed her. She said: "The Messenger of Allah (peace and blessings of Allah be upon him) would reach the morning, and then perform Witr."