Yahya related to me from Malik that Yahya ibn Said said that he
had heard al-Qasim ibn Muhammad say that Zayd ibn Abd al-Malik
separated some men and their wives who were slave-girls who had borne
children to men who had died, because they had married them after one
or two menstrual periods. He separated them until they had done an
idda of four months and ten days. Al-Qasim ibn Muhammad said, "Glory
be to Allah! Allah says in His Book, 'Those of you who die, leaving
wives, they are not wives.' "
Muwatta Malik Book 29, Hadith 101