Perfecting Islam

In Sahih Muslim, there is a hadith on the authority of Abu Huraira that describes the great reward for those people who complete and "perfect" their Islam. Abu Huraira narrated that the Prophet (peace be upon him) said,

"If one of you makes his faith excellent, he will be recorded for every good deed ten-fold to seven hundred fold. And for every evil deed he does, he will have recorded one similar to it, until he meets Allah."

According to ibn Rajab, every good deed will be recorded ten-fold. However, the increase upon that is determined by how much a person completes his faith. In other words, the purer his intention, the greater the deed he performed and so forth will lead the deed to being multiplied seven-hundred fold.A hadith in Sunan al-Nasai states,

"If a servant accepts Islam and completes his Islam, Allah will record for him every good deed that he performed before [his Islam] and Allah will erase for him every evil deed that he did before [his Islam]. Then everything after that will be according to a retribution. For every good deed, he will be recorded ten-fold up to seven hundred fold. And for every evil deed he will be recorded similarly [one] for it, unless Allah overlooks that for him." [Malik, Al-Nasai]

This hadith shows that a person will be rewarded for the good deeds that he performed before becoming Muslim. His evil deeds will also be erased after becoming Muslim. However, this is conditional. This is conditional upon the fact that he perfects or completes his Islam. That is, it is conditional that he remains away from the evil deeds after he becomes a Muslim.

Compiled From:
"Commentary on the Forty Hadith of an-Nawawi" - Jamaal al-Din Zarabozo, pp. 589, 590