Proverbs 15:6 In the house of the righteous is much treasure: . . .
Proverbs 21:20 There is treasure to be desired and oil in the dwelling of the wise;. . .
Oil in the Bible represented the presence of God and His gift of holy spirit. In the house of a believer you will find the great treasure of God's Word and the presence of God.
Yea, if thou criest after knowledge, and liftest up thy voice for understanding; If thou seekest her as silver, and searchest for her as for hid treasures; Then shalt thou understand the fear of the LORD, and find the knowledge of God. Proverbs 2:3-5