To be accepted, repentance requires giving up the sin and making amends, and Allah alone accepts repentance and forgives sins. These verses also speak of turning back to Allah in repentance (inabah), the command to repent joined to seeking forgiveness, sin committed in ignorance, and repentance that is no longer accepted at the moment of death.
Verses gathered from a topical index of the Quran, in Mushaf order; every verse is quoted in full.
And never is it for a believer to kill a believer except by mistake. And whoever kills a believer by mistake - then the freeing of a believing slave and a compensation payment [diyah] presented to his [i.e., the deceased's] family [is required], unless they give [up their right as] charity. But if he [i.e., the deceased] was from a people at war with you and he was a believer - then [only] the freeing of a believing slave; and if he was from a people with whom you have a treaty - then a compensation payment presented to his family and the freeing of a believing slave. And whoever does not find [one or cannot afford to buy one] - then [instead], a fast for two months consecutively, [seeking] acceptance of repentance from Allāh. And Allāh is ever Knowing and Wise.
Allāh will not impose blame upon you for what is meaningless in your oaths, but He will impose blame upon you for [breaking] what you intended of oaths. So its expiation is the feeding of ten needy people from the average of that which you feed your [own] families or clothing them or the freeing of a slave. But whoever cannot find [or afford it] - then a fast of three days [is required]. That is the expiation for oaths when you have sworn. But guard your oaths. Thus does Allāh make clear to you His verses [i.e., revealed law] that you may be grateful.
O you who have believed, do not kill game while you are in the state of iḥrām. And whoever of you kills it intentionally - the penalty is an equivalent from sacrificial animals to what he killed, as judged by two just men among you as an offering [to Allāh] delivered to the Kaʿbah, or an expiation: the feeding of needy people or the equivalent of that in fasting, that he may taste the consequence of his matter [i.e., deed]. Allāh has pardoned what is past; but whoever returns [to violation], then Allāh will take retribution from him. And Allāh is Exalted in Might and Owner of Retribution.