Imam Bukhari narrates: Muhammad bin Yusuf narrated to us, he said: Sufyan narrated to us from Aun bin Abi Juhaifah from his own father,
he saw Bilal, may Allāh be pleased with him, giving the Adhan, so I (also) turn my face here and there (right and left) in the Adhan, following Bilal.
Reference: Sahih Al Bukhari 634