Leviticus 22:29 (NKJV)
"And when you offer a sacrifice of thanksgiving to the Lord, offer it of your own free will."
Philippians 4:6 (NKJV)
"Be anxious for nothing, but in everything by prayer and supplication, with thanksgiving, let your requests be made known to God."
Malachi 3:16 (NKJV)
"Then those who feared the Lord spoke to one another, and the Lord listened and heard them; so a book of remembrance was written before Him for those who fear the Lord and who meditate on His name."