And it is narrated from Bilal (may Allah be pleased with him) that he inserted both his fingers into his ears during the call to prayer (adhan). And Abdullah bin Umar (may Allah be pleased with them both) did not insert his fingers into his ears during the adhan. And Ibrahim al-Nakha’i said that there is no harm in giving the adhan without ablution (wudu). And Ata said that ablution is necessary and Sunnah for the adhan. And Aisha (may Allah be pleased with her) said that the Messenger of Allah (peace and blessings be upon him) used to remember Allah at all times.

Narrated `Aun bin Abi Juhaifa: My father said, "I saw Bilal turning his face from side to side while pronouncing the Adhan for the prayer."