Muwatta Malik 290
موطأ مالك#290SahihYahya related to me from Malik from Abu'n-Nadr, the mawla of Umar ibn Ubaydullah from Yusr ibn Said that Zayd ibn Thabit said, "The most excellent prayer is your prayer in your house, except for the prescribed prayers
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Salim al-HilaliMauquf Sahih
In-book reference: 8:4