Why did Allaah The Almighty send Prophets and Messengers?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.

Allaah The Almighty sent the Prophets and Messengers so that people will have no argument against Him on the Day of Judgment in terms of saying that they did not receive His message. Some of the verses that prove this are :

1-      The verse where Allaah The Almighty Says (what means): {O People of the Scripture, there has come to you Our Messenger to make clear to you [the religion] after a period [of suspension] of messengers, lest you say, "There came not to us any bringer of good tidings or a warner." But there has come to you a bringer of good tidings and a warner.} [Quran 5:19]

2-      The verse where Allaah The Almighty Says (what means): {[We sent] messengers as bringers of good tidings and warners.} [Quran 4:165]

Commenting on this verse, Ibn Katheer mentioned that the Messengers promise those who obey Allaah The Almighty that they will be rewarded, and warn those who disobey Him that they will be punished.

3-      The verse where Allaah the Almighty Says (what means): {So that mankind will have no argument against Allaah after the messengers. And ever is Allaah Exalted in Might and Wise.} [Quran 4:165]

Allaah The Almighty ordered the Messengers to convey His message to people so that no one will have an excuse for not obeying Him. Allaah The Almighty Says (what means): {And if We had destroyed them with a punishment before him, they would have said, "Our Lord, why did You not send to us a messenger so we could have followed Your verses before we were humiliated and disgraced?"} [Quran 20:134]

In an authentic Hadeeth on the authority of Ibn Mas‘ood the Messenger of Allaah, sallallaahu ‘alayhi wa sallam, mentioned that Allaah The Almighty sent the Prophets as bearers of good tidings and warners so that no one will have an excuse on the Day of Resurrection for disobeying the commands of Allaah The Almighty. [Al-Bukhari and Muslim]

Allaah Knows best.