It was reported that Az-Zuhri said, concerning this Ayah, that Abu Hurayrah, may Allah be pleased with him, said, "The Messenger of Allah said:

«Allah rejoices more over the repentance of His servant than one of you feels when he finds his lost camel in a place where he had feared that he would die of thirst.»"

Hammam bin Al-Harith said, "Ibn Mas'ud was asked about a man who commits immoral sins with a woman and then marries her. He said, 'There is nothing wrong with that,' and recited:

{And He it is Who accepts repentance from His servants}."

{and forgives sins,} means, He will accept repentance in the future, and He forgives past sins.

{and He knows what you do.} means, He knows all your deeds and actions and words, yet He still accepts the repentance of those who repent to Him.

As-Suddi said, "This means, He responds to them." This was also the view of Ibn Jarir: "It means that He answers their supplication for themselves, their companions and their brothers."

means, after the people have given up hope that rain will fall, He sends it down upon them at their time of need. This is like the Ayah:

{and spreads His mercy.} means, He bestows it upon all the people who live in that region. Qatadah said, "We were told that a man said to 'Umar bin Al-Khattab, may Allah be pleased with him, 'O Commander of the faithful, no rain has come and the people are in despair.' 'Umar, may Allah be pleased with him, said, 'Rain will be sent upon you,' and he recited:

{And He it is Who sends down the rain after they have despaired, and spreads His mercy. And He is the Protector, Worthy of all praise}.'
Meaning He is the One Who is in control of His creation, taking care of what will benefit them in this world and the Hereafter, and the consequences of all His decrees and actions are good, for which He is worthy of all praise.