The first sermon the Prophet Muhammad gave was less than 2 minutes. There are two versions of the sermon. The first is from Qurtubi's book. Abu 'Abdullah Al-QurtubiorAbu 'Abdullah Muhammad ibn Ahmad ibn Abu Bakr al-Ansari al-Qurtubi lived in the thitheenth century.
The second is from Ibn Hisham, who lived in the ninth century. Ibn Hisham's book is based on his recollection of Ibn Ishaq's wok on the life of Prophet Muhammad. Here is the translation of the two versions of the sermon.
From Qurtubi's book
“All praise is due to Allah: I praise Him, ask only Him for help, and ask Him alone for guidance and His mercy. I have faith in Him only. Do not disbelieve in Him, despise those who deny Him, and I bear witness that there is no lord but Allah. He is alone. He has no equal. I bear witness that Muhammad ﷺ is His servant and His prophet. Allah sent him for guidance. His purpose was to show the right way, to show the light, and to give sincere advice and wisdom. He came at a time when there was no other prophet in the world. Knowledge was little. The majority of the people were not on the right path. The time was flying to its end, and the day of judgment was closer. It appeared that the time had concluded its period. Those who follow Allah or and His Blessed Prophet ﷺ find the right path. Those who disobey Allah and His Blessed Prophet ﷺ stray. They trespass the boundaries [set by Allah and His Blessed Prophet ﷺ] and have fallen in the abyss of deviation. I advise you to hold onto taqwa. The best advice a Muslim can give another is that he encourages him to prepare for the Hereafter. So, ask people to hold tight to the taqwa of Allah, and fear Allah the way He demands that you become conscious of Him. The best way to attain the things you desire in the Hereafter is to be mindful of Him. Allah will remember and honor the one in this world who perfects his relationship with the Creator in his public and private life and does so only to please Him. It will help him after death, on the day when he will be most in need of the good deeds he sent before him and on the day when he will wish his evil deeds were further from him. Allah tells you to be mindful of Him. He is merciful upon His servants. He is the Creator who spoke the truth and fulfilled His promise, which He always keep. Verily, Allah says, Things will not change before me, and I am not unjust upon humanity.“ ”Ruhal-Ma’ani, 14/101 | Tafsir al-Qurtubi, Ibn Al-Qayyim mentions the following in his famous book Zad Al-Ma’ad (Provisions of the Hereafter). Ibn Ishaq reported […]: “The Messenger of Allah ﷺarrived in Al-Madinah and stayed in Quba’ on Monday, Tuesday, Wednesday, and Thursday and built the mosque. He left on Friday and was in the land of Banu Salim Ibn ‘Awf when the time of Friday prayer approached. He prayed in their mosque. Ibn Ishaq said: “It was the first sermon which he delivered, according to Abu Salamah Ibn ‘Abdur-Rahman. We seek refuge with Allah from attributing to him anything which he did not say. He stood up among them and praised Allah and extolled Him; then, he said: “As for what follows, oh, you people! Send forth for yourselves (good deeds). You know for sure, by Allah, that a person among you will become unconscious, and he will leave his sheep without a shepherd. His Lord will surely say to him – and there will be neither intermediary nor screen between them: “Did not My Messenger come to you and communicate (the Message), and did I not give you wealth and favor you? And what did you send forth for yourself?”And indeed, he will look right and left, but he will see nothing; then, he will look in front of him, and he will see naught but the Hell-fire. Whoever can save his face from the Fire, even by giving a piece of a date in charity, let him do so. And whoever cannot do so, let him (shield it)by saying a kind word. The reward of a good deed is multiplied by ten times even a hundred times. And may the Peace, Mercy, and Blessings of Allah be upon you.” Ibn Ishaq said: “Then the Messenger of Allah ﷺ, delivered a second sermon, saying: “All praise and thanks be to Allah, I praise Him and I seek His Aid. We seek refuge with Allah from the evil of ourselves and the wickedness of our deeds. Whomsoever Allah guides, there is none can misguide him, and whomsoever Allah sends astray, there is none can guide him. And I testify that none has the right to be worshipped except Allah, Alone, without partners. The best of speech is the Book of Allah. He whose heart has been beautified with it by Allah and whom He has admitted to the fold of Islam after he had disbelieved will be successful, for he has chosen it (Allah’s Speech) over that of all of humankind. Truly, it is the best of speech and the most eloquent. Love what Allah loves; love Allah with all of your hearts. Do not become tired of Allah’s Speech, nor of mentioning His Name, and do not make your hearts hard towards it. Hence, amongst everything that Allah creates, He chooses [something]; Allah would call it: His Kherah (best) in terms of deeds; His favorite ones amongst the servants; that which is good and useful in terms of speech. So worship Allah and do not associate anything with Him and fear Him as He should be feared and be sincere to Allah in the righteous words which pass your lips and love one another with Allah’s Spirit between you. Verily, Allah does not want to break his Covenant should be broken. And may the Peace, Mercy, and Blessings of Allah be upon you.” (Source: ‘Zad Al-Ma’ad’.Mentioned by Ibn Hisham in ‘As-Seerah An-Nabawiyyah’ from Ibn Ishaq, but without any chain of narrators. See ‘Zad Al-Ma’ad’ vol. 1, page 374 published by Maktabah Al-Manar Al-Islamiyyah/ quoted by IqraSense)
JazakAllah khair brother