It is narrated from Sayyiduna Abu Umamah (may Allah be pleased with him) that Sayyiduna Ali (may Allah be pleased with him) said to the Messenger of Allah (peace and blessings be upon him): Give me a servant. He (peace and blessings be upon him) said: "There are three slaves in the house; choose one of them." He said: O Messenger of Allah, you choose for me yourself. He (peace and blessings be upon him) said: "Take this slave, for I have seen him praying ever since we set out; and do not beat him, for we have been forbidden to beat those who pray."
Hadith Referenceالمعجم الكبير للطبراني / باب الصاد / 8069