In it, only the chanting of Azan in the ear of Hazrat Hasan is mentioned, but in another Tradition quoted in Musnad-i- Abu ya’ali Mosuli, on the authority of Hazrat Husain bin Ali, and reproduced in Kanzu Ummal, it is told that the holy Prophet prescribed the saying of Azan in the right and Iqamat (or the second call to prayer just before the prayer commences) in the left ear of (the new-born child), and, also, explained its propitiousness. He said that, on account of it, the child remained safe from infantile epilepsy.
As these Traditions go to show, the primary claim of a child on his family was that his ears, and through the ears, his head and heart were made acquainted with the Name of God, and with His Oneness and the Call of Faith and Namaz. The best way to it, evidently, is that Azan and Iqamat were said in its ears, as these impart the knowledge of the spirit and fundamental tenets of Islam in a most effective manner.
The holy Prophet has enjoined the saying of Azan and Iqamat in the ears of a Muslim child, at the time of its birth, and the offering of Namaz-i-Janazah (Funeral prayer) when a Muslim dies and his body has been bathed and covered with a shroud and made ready for the burial. He has, thus, stressed that the life of a Muslim begins with Azan and ends with Namaz, and ought to be spent in the way it is done while waiting and preparing for Namaz after the Azan has been given. Besides, the foremost claim of a Muslim is that Azan is said in his ears at the time of his birth and the last is that Namaz-i-Janazah is offered over him when he passes away.
One of the manifestations of the deep devotion the Companions had for the Prophet was that when a child was born in their family, they brought it to him so that he might bless it, and apply, on its palate, the pulp of a date etc, he had chewed himself and drop the saliva in its mouth which, they believed, would have the effect of averting evil from the child and bringing it good fortune. It is called Tahnik in the Islamic parlance.