Is it reported that Gabriel descended with three banners on the day the Prophet (peace and blessings be upon him) was born, planting one on the Kaaba, another on Bayt al-Maqdis (Jerusalem), and a third on the house of Amina? And what is the authenticity of this statement?

This is false speech with no basis, and none of the people of knowledge or the people of Hadith (definition) have mentioned it. Therefore, it is not permissible to attribute it to Gabriel, peace be upon him, because he only descends by the command of his Lord. Whoever attributes that to him without knowledge has spoken falsely against Allah, and this is one of the gravest sins.