Peculiar People; Peculiar Treasure

Concise Bible Dictionary:

Except in Ecclesiastes 2:8, where “the peculiar treasure of kings” is gathered by Solomon, these expressions both in the Old Testament and in the New Testament refer to what God’s people are to Him (Ex. 19:5; Deut. 14:2; Deut. 26:18; Psa. 135:4; Titus 2:14). The terms imply a possession upon which a specially choice value is set. 1 Peter 2:9 is a little different: “Ye are a people for a possession.” (compare Mal. 3:17.)