سنن أبي داود

Jabir b. Samurah said: When we prayed behind the Messenger of Allah(ﷺ), one of us gave the salutation and pointed with his hand to the man to his right side and left side. When he finished his prayer, he said: What is the matter that one of you points with his hand (during prayer) just like the tails of restive horses. It is sufficient for one of you, or is it not sufficient for one of you to say in this manner? And he pointed with his finger; one should salute his brother at his right and left side.