After relating Abu Lahab’s relief on setting Thuwaybah free, the great scholar and muhaddith Shah Abdul-Haqq Dehlawi (rahmatullahi ‘alayhi) said in his famous book Madarij al-Nubuwwah:
“This event provides a clear proof to those who celebrate al-Mawlid al-Sharif by rejoicing and alms giving on the night of the birth of the holy Prophet ﷺ, People of Makkah gather on the 12th of Rabi’ al-Awwal to sit in the house in which the Prophet ﷺ was born. Only because he ﷺ was his nephew, he (Abu Lahab) has been receiving, in spite of this being an idolater, the benefits of thus rejoicing in his grave every Monday. Then how much more blessing will fall to the lot of him who acknowledges the Prophet ﷺ as the beloved of Allah ﷻ and His true Prophet, and celebrates al-Mawlid al-Sharif repeatedly?”
—Madarij al-Nubuwwah, vol. 2, Page 34, Publisher: Zia al-Quran Publication.