"Do not corrupt the Sunnah of our Prophet Muhammad (ﷺ). The waiting period of an Umm Walad is four months and ten (days)."
Sunan Ibn Majah Book 10, Hadith 68
← Previous Hadith "Ibn 'Abbas was asked about a slave who divorces his wife twice, then (they are freed). Can he marry her? He said: 'Yes.' It was said to him: 'On what basis?' He said: 'The Messenger of Allah (ﷺ) passed such a judgement .' " (D a' if)

Sunan Ibn Majah Book 10, Hadith 67 Next Hadith → he heard Zainab the daughter of Umm Salamah narrating that she heard Umm Salamah and Umm Habibah mention that a woman came to the Prophet (ﷺ) and said that her daughter's husband had died, and she was suffering from an eye disease, and she wanted to apply kohl to her eyes (as a remedy). The Messenger of Allah (ﷺ) said: "One of you would throw a she-camel's dropping when a year had passed (since the death of her husband. Rather it is four months and ten (days)."

Sunan Ibn Majah Book 10, Hadith 69