Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) narrated that a man asked, "O Messenger of Allah, will we be held accountable for the sins we committed during the time of ignorance (Jahiliyyah)?" He replied, "Whoever does good deeds after accepting Islam will not be held accountable for the sins of Jahiliyyah, but whoever continues to do evil even after becoming a Muslim will be held accountable for the sins of both periods."

Sayyiduna Ibn Abbas (may Allah be pleased with them both) narrated that among the polytheists, some had committed the sin of murder, and had done so excessively. Similarly, they used to commit adultery in abundance. Then they came to the Prophet Muhammad (peace and blessings be upon him) and said, "What you say and what you invite us to (i.e., Islam) is certainly a good thing, but tell us, will the sins we have committed so far be forgiven if we accept Islam or not?" Upon this, this verse was revealed: "And those who do not call upon any other god besides Allah, nor kill a soul which Allah has forbidden except by right, nor commit adultery. And whoever does this shall meet a severe penalty." (__QUR_25:68__) And this verse was revealed: "Say, 'O My servants who have transgressed against themselves, do not despair of the mercy of Allah. Indeed, Allah forgives all sins. Indeed, He is the Most Forgiving, Most Merciful.'" (__QUR_39:53__)

Sayyiduna Hakim bin Hizam (may Allah be pleased with him) narrated that I asked, "O Messenger of Allah (peace and blessings of Allah be upon him), what do you say about those good deeds which I used to do in the time of ignorance, such as giving charity, freeing slaves, and maintaining ties of kinship? Will I get a reward for them?" The Prophet (peace and blessings of Allah be upon him) said, "You have accepted Islam along with all those good deeds which you did before."

Sayyiduna Abdullah bin Mas’ud (may Allah be pleased with him) narrated that when the verse“Those who believe and do not mix their faith with injustice”(Al-An’am 82) was revealed, it was very hard on the Muslims and they said,“Who among us is there who has not mixed his faith with injustice?”The Prophet (peace and blessings of Allah be upon him) said,“It does not mean that. By injustice, what is meant in the verse is shirk (associating partners with Allah). Have you not heard that Luqman advised his son, ‘O my son, do not associate anything with Allah. Indeed, shirk is a great injustice’”(Luqman 13).

Sayyiduna Abu Hurairah (may Allah be pleased with him) narrated that the Prophet Muhammad (peace and blessings be upon him) said: Allah Almighty has forgiven my Ummah for evil thoughts as long as they do not act upon them or speak of them.

Sayyiduna Abu Hurairah (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) said: When any one of you perfects his Islam (i.e., purifies it from hypocrisy and show-off), then for every good deed he does, ten to seven hundred times rewards are written for him, and for every bad deed he does, only that much (i.e., equal to what he did) is written.

Sayyiduna Ibn Abbas (may Allah be pleased with them both) narrated that the Messenger of Allah (peace and blessings be upon him) said in a Hadith Qudsi: "Allah Almighty has decreed good deeds and bad deeds and then made them clear. So whoever intends to do a good deed but does not do it, Allah writes for him a complete good deed from tenfold to seven hundredfold, and even more. And whoever intends to do a bad deed but does not do it, Allah writes for him a complete good deed. But if he intends it and then acts upon it, Allah writes for him a single bad deed."

Sayyiduna Abu Hurairah (may Allah be pleased with him) narrated that the Messenger of Allah (peace and blessings be upon him) said: Satan comes to one of you and raises questions in your heart, first asking, "Who created such and such? Who created such and such?" until he finally says, "Who created your Lord?" When anyone experiences such a whisper, he should seek refuge with Allah and abandon that satanic thought.

Sayyiduna Anas bin Malik (may Allah be pleased with him) narrated that the Messenger of Allah (peace and blessings of Allah be upon him) said: A person will continue to ask questions until he will ask: "This is Allah, the Creator of everything, but who created Allah?" (God forbid, Satan will cast this doubt into their hearts).

Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) narrated that the Messenger of Allah (peace and blessings be upon him) said: Whoever swears an oath in order to unlawfully take the wealth of a Muslim (by lying), then when he meets Allah, Allah will be extremely angry with him. Then Allah the Exalted revealed this verse to confirm your statement: "Indeed, those who exchange the covenant of Allah and their oaths for a small price, there will be no share for them in the Hereafter. Allah will neither speak to them nor look at them on the Day of Resurrection, nor will He purify them, and for them is a painful punishment." (Aal-e-Imran 77) The narrator stated that Sayyiduna Ash'ath bin Qais (may Allah be pleased with him) came and asked, "Has Abu Abdur Rahman (Sayyiduna Abdullah bin Mas'ud, may Allah be pleased with him) narrated any hadith to you?" We replied, "Yes, he has narrated the hadith in this manner." Ash'ath said, "This verse was revealed about me. I had a well in the land of my cousin (we had a dispute about it and the case was presented before the Prophet, peace and blessings be upon him). The Prophet said to me, 'Either you present evidence, or the decision will be made on his oath.' I said, 'O Messenger of Allah, then he will take a (false) oath.' The Prophet said, 'Whoever swears a false oath in order to unlawfully take the wealth of a Muslim, and his intention is evil, he will meet Allah in such a state that Allah will be extremely angry with him.'"