How is the phrase: "Some of the Salaf said her supplication is answered, even if she is an oppressor" to be explained, knowing that Allah has forbidden injustice upon Himself, and that He does not answer the supplication of a mother who unjustly supplicates against her son without cause?

The supplication of a parent for or against their child is answered, except in two cases: if it is made in a moment of anger and vexation, or if the parent is unjust. It is mentioned in a Hadith (definition) in Bukhari that the supplication of the Jews against the Prophet, peace and blessings be upon him, was not answered because they supplicated unjustly, and the supplication of the disbelievers is astray. An exception to this is the supplication of a mother against her child, as in the story of Jurayj; his mother was not unjust, rather it was proper for him to answer her. The more apparent view is that the supplication of an unjust parent is not answered. One must beware of the supplication of parents.