It was narrated that Anas bin Malik said:
"What the Messenger of Allah (ﷺ) most enjoined when he was dying and breathing his last was: The prayer; and those whom your right hands possess." (TR)
English reference (TR): Vol. 3, Book 22, Hadith 2697 (TR)
Arabic reference (TR): Book 22, Hadith 2801 (TR)