After receiving the divine revelation, the Prophet [Peace be upon him] started to preach the message of Islam to his close family and friends. Khadijah, Abu Bakr, Ali, Zaid [May Allah be pleased with them all] were amongst the first ones to embrace Islam.
The Prophet [Peace be upon him] continued to preach secretly for 3 years until Allah commanded him to spread the message of truth openly and publicly.
Allah says: [وأنذر عشيرتك الأقربين]
And warn (O Muhammed) your nearest kindred. [26:214]
One day the Prophet (ﷺ) ascended Safa mountain and said, “Oh Sabah! ” All the Quraish gathered round him and said, “What is the matter?” He said, Look, if I told you that an enemy is going to attack you in the morning or in the evening, would you not believe me?” They said, “Yes, we will believe you.” He said, “I am a warner to you in face of a terrible punishment.” On that Abu Lahab said, “May you perish ! Is it for this thing that you have gathered us?” …
[Bukhari Book 65 Hadith 4801]
On his statement Allah revealed Surah Masad where He informed of Abu Lahab’s severe punishment which he earned by insulting the Messenger of Allah and rejecting the divine message:
[Perish the hands of the Father of Flame! Perish he! (1) No profit to him from all his wealth, and all his gains! (2) Burnt soon will he be in a Fire of Blazing Flame! (3)] 111:1-3
After the Prophet [Peace be upon him] started preaching publicly, the number of people entering the fold of Islam started increasing day by day. The Quraiysh became fearful of the new religion their people were becoming committed to. They wanted the religion of their forefathers to prevail over Arabia for as long as possible. They knew the new religion Mohammad was preaching didn’t allow them to practice any immoral and corrupt laws. They decided to stop people from converting to Islam by torturing the newly converted Muslims.