2 look to Abraham, your father, and to Sarah, who gave you birth. When I called him he was only one man, and I blessed him and made him many.

Read Isaiah 51:2 Using Other Translations

Look unto Abraham your father, and unto Sarah that bare you: for I called him alone, and blessed him, and increased him.
Look to Abraham your father and to Sarah who bore you; for he was but one when I called him, that I might bless him and multiply him.
Yes, think about Abraham, your ancestor, and Sarah, who gave birth to your nation. Abraham was only one man when I called him. But when I blessed him, he became a great nation.”