Reference: Peculiar People, Or Treasure
Except in Ec 2:8, where 'the peculiar treasure of kings' is gathered by Solomon, these expressions both in the O.T. and in the N.T. refer to what God's people are to Him. Ex 19:5; De 14:2; 26:18; Ps 135:4; Tit 2:14. The terms imply a possession upon which a specially choice value is set. 1Pe 2:9 is a little different "Ye are 'a people for a possession': cf. Mal 3:17.
Now if you will listen to Me and carefully keep My covenant, you will be My own possession out of all the peoples, although all the earth is Mine,
for you are a holy people belonging to the Lord your God. The Lord has chosen you to be His special people out of all the peoples on the face of the earth.
And today the Lord has affirmed that you are His special people as He promised you, that you are to keep all His commands,
For the Lord has chosen Jacob for Himself, Israel as His treasured possession.
I also amassed silver and gold for myself, and the treasure of kings and provinces. I gathered male and female singers for myself, and many concubines, the delights of men.
"They will be Mine," says the Lord of Hosts, "a special possession on the day I am preparing. I will have compassion on them as a man has compassion on his son who serves him.
He gave Himself for us to redeem us from all lawlessness and to cleanse for Himself a special people, eager to do good works.
But you are a chosen race, a royal priesthood, a holy nation, a people for His possession, so that you may proclaim the praises of the One who called you out of darkness into His marvelous light.