Those who said declaring her unlawful is an oath and not a divorce

Sayyiduna Umar (may Allah be pleased with him) said: If a man says to his wife, "You are forbidden (haram) to me," it has the ruling of an oath.

The same is reported through another chain.

Sayyidah Aishah (may Allah be pleased with her) said: If a man says to his wife, "You are forbidden (haram) to me," it has the ruling of an oath.

Sayyiduna Ibn Abbas (may Allah be pleased with them both), Jabir bin Zayd, Sa'id bin Jubayr, Sa'id bin al-Musayyib and Sulayman bin Yasar said: If a man says to his wife, "You are forbidden (haram) to me," it has the ruling of an oath.

Abu Salamah (may Allah have mercy on him) said: Declaring a woman forbidden and declaring fresh water forbidden are the same (to me).

Ata (may Allah have mercy on him) and Tawus (may Allah have mercy on him) said: If a man says to his wife, "You are forbidden (haram) to me," it has the ruling of an oath.

Abu Qilabah (may Allah have mercy on him) said: Some people say that declaring one's wife forbidden makes three divorces take effect, and some say that the expiation of an oath must be given, whereas my view is that the expiation of zihar must be given.

Sa'id (may Allah have mercy on him) and Abu Ja'far (may Allah have mercy on him) said: If a man says to his wife, "You are forbidden (haram) to me," it has the ruling of an oath.

And through Hajjaj from Abu Ja'far: they both (Sa'id and Abu Ja'far) said: Declaring (one's wife) forbidden is an oath.

Sayyiduna Ibn Abbas (may Allah be pleased with them both) said: If a man says to his wife, "You are forbidden (haram) to me," it has the ruling of an oath, and Allah Almighty has ordained for you the expiation of your oaths.

Makhul (may Allah have mercy on him) and Sulayman bin Yasar (may Allah have mercy on him) said: If a man says to his wife, "You are forbidden (haram) to me," it has the ruling of an oath.

Masruq (may Allah have mercy on him) said: To me, declaring a woman forbidden and declaring a bowl of tharid forbidden are the same.

Sayyiduna Abu Bakr and Sayyiduna Ibn Mas'ud (may Allah be pleased with them both) said: If a man says to his wife, "You are forbidden to me," she does not become forbidden to him; he must give the expiation of an oath.

Al-Sha'bi (may Allah have mercy on him) said: If a man says to his wife, "You are forbidden (haram) to me," it is nothing.

Amir (al-Sha'bi) (may Allah have mercy on him) said: People claim that the position of Sayyiduna Ali (may Allah be pleased with him) was that if a man declares his wife forbidden to himself, three divorces take place, and the woman is not lawful for that husband until she marries another man. By Allah! Sayyiduna Ali (may Allah be pleased with him) never said that, and I know more about it than the one who said it. Sayyiduna Ali (may Allah be pleased with him) said: "I neither declare her lawful nor forbidden; if he wishes, let him go ahead, and if he wishes, let him hold back."

Sa'id bin Jubayr (may Allah have mercy on him) said: If a man says to his wife, "You are forbidden (haram) to me," he should free a slave, and if he said this to four wives, he should free four slaves.