Мидраш к Мишлей 31:28

Her children rise up, and call her blessed (Prov. 31:28); And she said: Who would have said unto Abraham that Sarah should give children suck? For I have born him a son in his old age (Gen. 21:7). Many daughters have done valiantly (Prov. 31:29) refers to the nations, But thou excellest them all (ibid.) alludes to Sarah, as it is said: Look unto Abraham, your father, and to Sarah, that bore you (Isa. 51:2). Give her of the fruit of her hand (Prov. 31:31), for it is said: And the life of Sarah was a hundred and twenty and seven years (Gen. 23:1).