"Enter His gates with thanksgiving, and His courts with praise." Rabbi Pinchas said in the name of Rabbi Levi, "All sacrifices may be discontinued, but the sacrifice of thanksgiving will never be discontinued, as it is written (Psalms 56:13), 'I will render thanksgiving offerings to You.' Two offerings are mentioned, one in reference to prayer, and the other in reference to sacrifice." And likewise it says (Jeremiah 33:11), "A voice of joy and a voice of gladness... the voice of those who bring thanksgiving to the Lord's house."
Behold, the prayer of thanksgiving. And it says, "And bring thanksgiving to the house of the Lord," which is the sacrifice of thanksgiving. "Give thanks to Him, bless His name," behold the prayer of thanksgiving. As it is written, "For the Lord is good, His lovingkindness endures forever."