Musannaf Ibn Abi Shaybah

Hazrat Abdullah (may Allah be pleased with him) narrates that when Hazrat Umar (may Allah be pleased with him) adopted an opinion and then we adopted that opinion, we found it to be easy. Thus, he was asked about (inheritance shares of) the wife and the parents, so he said: For the wife, one-fourth; for the mother, one-third of the remaining wealth; and whatever remains after that is for the father.