أُمّهُمْ

Appears 2 times in the Quran. (Root: امم)
  1. The Prophet has a greater claim on the faithful than they have on themselves, and his wives are (as) their mothers; and the possessors of relationship have the better claim in the ordinance of Allah to inheritance, one with respect to another, than (other) believers, and (than) those who have fled (their homes), except that you do some good to your friends; this is written in the Book.

  2. (As for) those of you who put away their wives by likening their backs to the backs of their mothers, they are not their mothers; their mothers are no others than those who gave them birth; and most surely they utter a hateful word and a falsehood and most surely Allah is Pardoning, Forgiving.