Sahih al-Bukhari Book 68, Hadith 38
Allah's Messenger (ﷺ) took an oath that he would abstain from his wives, and at that time his leg had been
sprained (dislocated). So he stayed in the Mashruba (an attic room) of his for 29 days. Then he came
down, and they (the people) said, "O Allah's Messenger (ﷺ)! You took an oath to abstain from your wives for
one month." He said, "The month is of twenty nine days."
(the wife of the Prophet) When believing women came to the Prophet (ﷺ) as emigrants, he used to test them in accordance with the order of Allah. 'O you who believe! When believing women come to you as emigrants, examine them . . .' (60.10) So if anyone of those believing women accepted the above mentioned conditions, she accepted the conditions of faith. When they agreed on those conditions and confessed that with their tongues, Allah's Messenger (ﷺ) would say to them, "Go, I have accepted your oath of allegiance (for Islam). By Allah, and hand of Allah's Messenger (ﷺ) never touched the hand of any woman, but he only used to take their pledge of allegiance orally. By Allah, Allah's Messenger (ﷺ) did not take the pledge of allegiance of the women except in accordance with what Allah had ordered him. When he accepted their pledge of allegiance he would say to them, "I have accepted your oath of allegiance."
Ibn `Umar used to say about the Ila (which Allah defined (in the Holy Book), "If the period of Ila expires, then the husband has either to retain his wife in a handsome manner or to divorce her as Allah has ordered."