or ward off a harm from him.
Consequently, his testimony is ruled inadmissible in the following cases: on behalf of his own slave or contractual slave (mukātab); for a debtor of his who has died or has been placed under interdiction because of bankruptcy; in any matter in which he is acting as an agent; to secure the acquittal of a person whose liability he has guaranteed; or concerning an injury—or retaliation for it—suffered by someone from whom he stands to inherit.
If, however, he testifies for an ancestor of his who is ill or wounded, claiming a monetary right before the wound has healed, the sounder opinion is that such testimony is accepted.
The testimony of the ʿaqīlah (the paternal blood-money group) is rejected in homicide cases, as is that of the creditors of an insolvent debtor regarding a different debt.

If two witnesses give testimony that a deceased person made a bequest to two other individuals, and those two later testify that the deceased likewise made a bequest to the first pair from the same estate, both sets of testimony are accepted according to the sounder view.
No testimony is accepted in favor of a direct ascendant or descendant, although it is accepted against them—and likewise against their father in matters such as his divorcing a co-wife of their mother or accusing her of adultery, as is the sound position.
When a person testifies in favor of both his own descendant and an unrelated third party, the testimony is accepted for the outsider according to the stronger opinion.

I say: Testimony is also accepted in favor of either spouse, or of a brother or a close friend—Allah knows best.
It is not accepted from an enemy, defined as one who hates a person to the extent that he wishes for his blessings to vanish, is saddened by his happiness, and rejoices at his misfortune.
It is, however, accepted both for and against someone where the enmity is religious in nature—for example, between a Muslim and a non-Muslim, or between an adherent of the Sunnah and an innovator (mubtadiʿ).
The testimony of an innovator whom we do not deem an unbeliever is accepted, provided he is neither simple-minded, nor careless in accuracy, nor overly hasty.

Unsolicited testimony offered as ḥisbah is admissible in the rights of Allah Most High and in matters that involve a firmly established divine right, such as divorce, emancipation, pardon from retribution, the continuation or completion of a waiting period (ʿiddah), and the establishment of a ḥadd penalty.
The same applies to questions of lineage, according to the sound position.

If a judgment has been rendered on the basis of two witnesses and it later emerges that they were unbelievers, slaves, or minors, the judge who issued the ruling—and any other judge—must annul it; the same holds, according to the stronger view, when they are discovered to have been morally corrupt (fāsiq).
Should a non-Muslim, a slave, or a minor testify and then repeat the testimony after embracing Islam, emancipation, or attaining majority, it is accepted; but if an immoral person repeats the same testimony after having repented, it is not.
Fresh testimony from him is admissible only after he has been observed for a period sufficient to give reasonable confidence in the sincerity of his repentance—most scholars set this at one year.

Repentance from a verbal sin must itself be verbal: the slanderer, for example, must say, “My slander was false; I regret it and will never return to it,” and the same applies to false testimony.

I add: For non-verbal sins, repentance requires ceasing the act, feeling remorse, resolving never to repeat it, and, where another person’s right is involved, restoring that right. Allah knows best.