While barren, she gave her Egyptian maid Hagar to Abraham to bear his children
... 
Genesis 25:21 And Isaac entreated the LORD for his wife, because she was 
barren:  [DOC] [TLE] Genesis 16 - Hagar and the Birth of Ishmael - Bible Hub [PAR] So in an effort to help God fulfill His own promise she allowed her husband ... 
Then Sarai, Abram's wife, took Hagar her maid, the Egyptian, and gave her to ... 
And when she saw that she had conceived, her mistress became despised in her 
eyes.