Thanksgiving by definition means to express gratitude towards God. Thanksgiving was central to the Jewish faith and an essential part of worship according to the Old Testament. It was offered generally by the Jews in response to God’s concrete acts in history but sacrifice and offerings were also to be given continually out of a grateful heart.
In the Old Testament it is taught that thanksgiving should never be given grudgingly but always with a generous and willing heart. In Judeo-Christian tradition it is the duty of the faithful to express thankfulness to God for His constant love, care, provision and mercy. The praises of His people were considered the most valuable sacrifice of all, more pleasing to Him than the blood of animals.
I will I will praise the name of God with a song, and will magnify Him with thanksgiving. This also shall please the LORD better
than than an ox or bull, which has horns and hooves. Ps 69:30-31 (NKJV)
The Old Testament Law called for constant and continual thanks to be offered before the Lord. In the eras of the Jewish Tabernacle and Temple certain Levites were appointed to give continual praise and thanks to God.
He appointed certain of the Levites to minister before the Ark by giving constant praise and thanks to the Lord God of Israel and by asking for his blessings upon his people. (1Chronicles 16:4, tlb).
In the New Testament believers are also taught that praise and thanksgiving should be a regular part of our routine
Rejoice always, pray without ceasing, in everything give thanks; for this is the will of God in Christ Jesus for you. 1Thes 5:16-18 (NKJV)
It is good to make thankfulness a habitual part of our worship of God and to bless Him regularly with the expressive and spontaneous fruit of our lips.
It is good to say thank you to the Lord, to sing praises to the God who is above all gods. Every morning tell him, “Thank you for your kindness,” and every evening rejoice in all his faithfulness. Sing his praises, accompanied by music from the harp and lute and lyre. You have done so much for me, O Lord. No wonder I am glad! I sing for joy. O Lord, what miracles you do! And how deep are your thoughts! Psalms 92:1-5 (TLB)