Is a man's saying to his father, "How did my wife conceive when I did not ejaculate inside?"—a question about how conception occurred—considered a slander (qadhf), a mutual imprecation (li'an), or a denial of the child's lineage, and does anything ensue from it?

The man's words do not contain an explicit accusation of adultery against his wife, but they do allow for the insinuation of it. If he intended to insinuate adultery, he must repent. There is also no explicit denial of the child's lineage, so the child is his because he was born on his bed. His lineage can only be denied through li'an (oath of condemnation) according to specific regulations.