Stones made children of Abraham.

Matt. 3:9.

Vain are the hopes that rebels place
Upon their birth and blood,
Descended from a pious race;
Their fathers now with God.

He from the caves of earth and hell
Can take the hardest stones,
And fill the house of Abram well
With new-created sons.

Such wondrous power doth he possess
Who formed our mortal frame,
Who called the world from emptiness,
The world obeyed and came.

Isaac Watts

http://www.poemhunter.com/poem/hymn-99/