Albert Barnes on 1 Peter 2:6

Wherefore also it is contained in the scripture. Isa 28:16. The quotation is substantially as it is found in the Septuagint.

Behold, I lay in Sion. Isa 28:16, and Rom 9:33.

A chief corner-stone. The principal stone on which the corner of the edifice rests. A stone is selected for this which is large and solid, and, usually, one which is squared, and wrought with care; and as such a stone is commonly laid with solemn ceremonies, so, perhaps, in allusion to this, it is here said by God that he would lay his stone at the foundation. The solemnities attending this were those which accompanied the great work of the Redeemer. See the word explained in the Eph 2:20.

Elect. Chosen of God, or selected for this purpose, 1Pet 2:4.

And he that believeth on him shall not be confounded. Shall not be ashamed. The Hebrew is, "shall not make haste." See it explained Rom 9:33.

(a) "Behold" Isa 28:16