Because it is contained in Scripture, "Behold, I lay in Zion a chief cornerstone, chosen, and precious: He who believes in him will not be disappointed."
(20) Several copies have ἡ γραφὴ instead of ἐν τὣ γραφὴ; and this reading Calvin has followed. But the verb περιέχω is used by Josephus and others in a passive sense. — Ed. 