Surah Ash-Shu'araa (26) — Ayah 107

(Ayah 108,107){ اِنِّيْ لَكُمْ رَسُوْلٌ اَمِيْنٌ …:} As proof of his claim to prophethood, Noah (peace be upon him) presented two things: first, that I am trustworthy, my entire life has passed before you, you are well aware of my trustworthiness and my truthfulness, then what is the obstacle for you in accepting my prophethood? Allah Almighty also commanded our Prophet (peace and blessings be upon him) to state this matter in clear words, He said: «{ فَقَدْ لَبِثْتُ فِيْكُمْ عُمُرًا مِّنْ قَبْلِهٖ اَفَلَا تَعْقِلُوْنَ }» [ یونس : ۱۶ ] "So indeed, I have lived among you a lifetime before this, then do you not understand?" In the hadith of Heraclius, when Abu Sufyan acknowledged the truthfulness and trustworthiness of the Messenger of Allah (peace and blessings be upon him), Heraclius said: "It is not possible that he would avoid lying to people, yet fabricate a lie against Allah that He has sent me as a Messenger." (See Bukhari: 7) In short, Noah (peace be upon him) informed his people of his prophethood by referring to his being trustworthy and said (since I am a trustworthy Messenger), therefore fear Allah, lest by denying me you become the target of His wrath, and obey what I say. It is thus understood that obeying every command of the Messenger is necessary for the Ummah. It is not that he merely conveys a few verses of the Book of Allah and that is sufficient, and apart from that, obeying him is not obligatory.