Hadith 431
وَحَدَّثَنِي عَنْ مَالِكٍ، أَنَّهُ بَلَغَهُ أَنَّ أَبَا بَكْرٍ، وَعُمَرَ، كَانَا يَفْعَلاَنِ ذَلِكَ .
Yahya related to me from Malik that he had heard that Abu Bakr and Umar used to do that
Mauquf Sahih (Salim al-Hilali)
Muwatta Malik 431 · Book 10, Hadith 4