Musnad Ahmad 1153:1598

Yahya narrated to us, from Shu'bah, who said: Al-Hakam narrated to me, saying: I said to Miqsam, "I perform Witr with three [rak'ahs], then I go out to the prayer fearing that I might miss it." He said, "There is no Witr except with five or seven." He said: So I mentioned that to Yahya ibn al-Jazzar and Mujahid, and they both said to me, "Ask him: from whom?" So I said to him [Miqsam], and he said: From the trustworthy one, from 'Aishah and Maymunah, from the Prophet, may Allah bless him and grant him peace.