Uttering the adhan in the ears of a newborn baby

I saw the Messenger of Allah ﷺ uttering the adhan in the ear of al-Hasan b. Ali when Fatimah gave birth to him.  

رَأَيْتُ رَسُولَ اللَّهِ ﷺ أَذَّنَ فِي أُذُنِ الْحَسَنِ بْنِ عَلِيٍّ حِينَ وَلَدَتْهُ فَاطِمَةُ بِالصَّلاَةِ  

Boys used to be brought to the Messenger of Allah ﷺ, and he would invoke blessings on them. Yusuf added: "and soften some dates and rub their palates with them". He did not mention "blessings".  

كَانَ رَسُولُ اللَّهِ ﷺ يُؤْتَى بِالصِّبْيَانِ فَيَدْعُو لَهُمْ بِالْبَرَكَةِ زَادَ يُوسُفُ وَيُحَنِّكُهُمْ وَلَمْ يَذْكُرْ بِالْبَرَكَةِ  

The Messenger of Allah ﷺ said to me: Have the mugharribun been seen (or some other word) among you? I asked: What do the mugharribun mean? He replied: They are those in whom is a strain of the jinn.  

لِي رَسُولُ اللَّهِ ﷺ هَلْ رُئِيَ أَوْ كَلِمَةً غَيْرَهَا فِيكُمُ الْمُغَرِّبُونَ قُلْتُ وَمَا الْمُغَرِّبُونَ قَالَ الَّذِينَ يَشْتَرِكُ فِيهِمُ الْجِنُّ