Ibrahim (may Allah have mercy on him) narrates from Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) concerning a man who said to his wife: "If she does such-and-such, she is divorced," and she then does it. He said: "It is one divorce, and the husband has the right to take her back."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الخلع والطلاق / 15090
Hammad bin Abi Sulayman (may Allah have mercy on him) reports from Ibrahim (may Allah have mercy on him) concerning a man who says to his wife: "She is divorced after a year." He said: "She is his wife; he may enjoy her for a year."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الخلع والطلاق / 15091
Jabir (may Allah have mercy on him) narrates from al-Sha'bi (may Allah have mercy on him) concerning a man who said to his wife: "When Ramadan begins, you are divorced." He said: "She remains his wife from the day he pronounced the divorce until Ramadan begins."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الخلع والطلاق / 15092
Ibn Abi al-Zinad (may Allah have mercy on him) narrates from his father (may Allah have mercy on him), who narrates from the jurists of Madinah, that if a man said to his wife: "If you go out of the house before night, you are divorced," and his wife went out of the house; or he said that about his slave, and the slave left before night without informing him, then the woman is divorced and the slave is freed, because he omitted to make an exception. He was negligent in making the exception, so his negligence is held against him.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الخلع والطلاق / 15093