Each Prophet AS was commissioned by Allah and tasked with preaching the true message of Allah,

وَإِلَىٰ عَادٍ أَخَاهُمْ هُودًا ۚ قَالَ يَـٰقَوْمِ ٱعْبُدُوا۟ ٱللَّهَ مَا لَكُم مِّنْ إِلَـٰهٍ غَيْرُهُۥ

To the people of ‘Ad We sent their brother Hud. He said: “O my people! Worship Allah, you have no god but Him; [Hud 11: 50]

وَإِلَىٰ ثَمُودَ أَخَاهُمْ صَـٰلِحًا ۚ قَالَ يَـٰقَوْمِ ٱعْبُدُوا۟ ٱللَّهَ مَا لَكُم مِّنْ إِلَـٰهٍ غَيْرُهُۥ

To the Thamud people, We sent their brother Saleh. He said: “O my people! Worship Allah, you have no god but Him. [Hud 11: 61]

The list will go on as each prophet was assigned with the one task, calling towards the Oneness of Allah.

The Last and most revered Prophet of Allah, Muhammed ﷺ was also given the same task – of inviting the people towards Tawheed – or the Oneness of Allah.

قُلْ هَـٰذِهِۦ سَبِيلِىٓ أَدْعُوٓا۟ إِلَى ٱللَّهِ ۚ عَلَىٰ بَصِيرَةٍ أَنَا۠ وَمَنِ ٱتَّبَعَنِى ۖ وَسُبْحَـٰنَ ٱللَّهِ وَمَآ أَنَا۠ مِنَ ٱلْمُشْرِكِينَ

Say, O Prophet, “This is my way. I invite to Allah with insight—I and those who follow me. Glory be to Allah, and I am not one of the polytheists.” [Yusuf 12: 108]

The Noble Messenger of Allah thus made it his life-long mission to invite the people towards Allah and he left no stone unturned while experiencing every type of difficulty and hardship in his quest to fulfil his mission.

The Prophet of Allah ﷺ did such due diligence in carrying out his duty of preaching the truth that even the verses of the Holy Quran were revealed asking him not to finish himself in his desire for the Kuffar (disbelievers) to accept Islam.

لَعَلَّكَ بَـٰخِعٌ نَّفْسَكَ أَلَّا يَكُونُوا۟ مُؤْمِنِينَ

O Muhammad, you will perhaps fret yourself to death with grief because they do not believe. [Ash Shua`raa 26: 3]

History and Seerah are filled with many incidents which show how the Prophet ﷺ used every opportunity, tolerated every form of criticism, with-stood every kind of abuse and forewent every type of pain and torture in order to convey the message of Allah to the people.

وعن أنس رضي الله عنه قال‏:‏ كان غلام يهودي يخدم النبي صلى الله عليه وسلمى الله عليه وسلم الله عليه وسلم فمرض فأتاه النبي صلى الله عليه وسلم الله عليه وسلم الله عليه وسلم يعوده، فقعد عند رأسه فقال له‏:‏ ‏ “‏أسلم‏”‏ فنظر إلي أبيه وهو عنده‏؟‏ فقال‏:‏ أطع أبا القاسم، فأسلم، فخرج النبي صلى الله عليه وسلمى الله عليه وسلم الله عليه وسلم وهو يقول‏:‏ الحمد لله الذي أنقذه من النار

Hadhrat Anas RA reported: A young Jewish boy who was in the service of the Prophet (ﷺ) fell ill. The Prophet (ﷺ) went to visit him. He sat down by his head and said to him, “Embrace Islam.” The little boy looked at his father who was sitting beside him. He said: “Obey Abul-Qasim (i.e., the Messenger of Allah (ﷺ)).” So he embraced Islam and the Prophet (ﷺ) stepped out saying, “Praise be to Allah Who has saved him from Hell-fire.” [Al-Bukhari].

The Messenger of Allah ﷺ only knew happiness when someone accepted Islam and his sadness was when a disbeliever died out of Islam. It is for this very reason that the Prophet ﷺ told Hadhrat Ali RA:

Narrated Hadhrat Sahl bin Sa`d RA: Allah’s Messenger ﷺ said, “Tomorrow I will give the flag to a man with whose leadership Allah will grant (the Muslim) victory.” So the people kept on thinking the whole night as to who would be given the flag. The next morning the people went to Allah’s Messenger (ﷺ) and every one of them hoped that he would be given the flag. The Prophet (ﷺ) said, “Where is `Ali bin Abi Talib?” The people replied, “He is suffering from eye trouble, O Allah’s Messenger (ﷺ).” He said, “Send for him and bring him to me.” So when `Ali came, the Prophet (ﷺ) spat in his eyes and invoked good on him, and be became alright as if he had no ailment. The Prophet (ﷺ) then gave him the flag. `Ali said, “O Allah’s Messenger (ﷺ)! Shall I fight them (i.e. enemy) till they become like us?” The Prophet (ﷺ) said, “Proceed to them steadily till you approach near to them and then invite them to Islam and inform them of their duties towards Allah which Islam prescribes for them, for by Allah, if one man is guided on the right path (i.e. converted to Islam) through you, it would be better for you than (a great number of) red camels.”