Deuteronomy 8:10
When thou hast eaten and art full, then thou shalt bless the LORD thy God for the good land which he hath given thee. When thou hast eaten and art full, then thou shalt bless the LORD thy God for the good land which he hath given thee.
In its setting, the instruction belongs to God's requirements in Deuteronomy 8:1-15 given to Israel as they entered the land, as part of His expressed will to be remembered and obeyed. It called them to remember His deliverance from Egypt and His care and to keep His commandments in the land. When satisfied after eating the food and abundance of the good land God has given, His people are to bless Him and thank Him, recognizing Him as the giver. That thanksgiving should match the abundance of the favors and blessings freely bestowed, warning against receiving God's gifts without giving Him thanks.
This gratitude goes together with remembering God and keeping His commandments, especially because prosperity can tempt His people to forget that their blessings come from Him. In the wider context of verses 10-20, the prosperity and happiness of Israel in the good land depended on strict obedience to every principle of God's law. The blessings were not grounds for self-satisfaction or disloyalty, but called for recognizing His mercy and obeying Him, while unthankfulness and selfishness led Israel to transgress His law. As the Lord's words, the chapter and its instruction apply to God's people today as surely as to Israel, written for the admonition of those living at the end of the world.