Hadith.5079 - It has been narrated: "Indeed, the husband is considered one of the witnesses."
The author of this book, may Allah سبحانه وتعالى have mercy on him, said:
These two narrations are in agreement and not contradictory. This is because whenever four people testify against a woman for adultery, and one of them is her husband who does not deny his child, the husband is counted as one of the witnesses.
However, if he denies his child while testimony is established against her for adultery, the three others are to be flogged with the legal punishment, and the husband must perform lian (mutual cursing) with her, leading to their separation, and she will never be permissible for him again.
This is because lian only occurs when the child is denied.
Additionally, if a slave accuses a free person of adultery, he is to be flogged eighty lashes because this falls under the rights of the people.