Genesis 8:21
And the LORD smelled a sweet savour; and the LORD said in his heart, I will not again curse the ground any more for man’s sake; for the imagination of man’s heart is evil from his youth; neither will I again smite any more every thing living, as I have done.
After leaving the ark, Noah's first act was to build an altar and offer burnt offerings from every kind of clean beast and clean fowl. God's smelling a sweet savour means He accepted that offering with pleasure, as it rose before Him and was received by Him. The offering expressed gratitude for deliverance and preservation through the Flood and faith in Christ as the great sacrifice.
In response God blessed Noah and his family, and through them all who would ever live on the earth, promising never again to curse the ground for man's sake nor to smite every living thing as He had done. He keeps that promise by sustaining human life, sending rain and sunshine by miracle-working power to make cultivated seed grow from blade to ear to full grain for bread, providing the materials for the loaf and daily feeding thousands and ten times ten thousand out of mercy and compassion even though the imagination of the heart is evil from youth. The chapter is inspired Scripture and factual history of Noah and the Flood. It demonstrates the fulfillment of God's warning that those who refused to obey His commandments perished while the obedient found shelter in the ark, showing that human perversity brings divine judgment, and its account of human nature in Noah's day applies to the present age when people are uninfluenced by the Spirit and the same kind of sins are increasing.
The verse teaches all succeeding generations to put God first before providing for themselves, making grateful thanks and humble worship the first response to every display of mercy and love, giving cheerfully to the Lord and His cause even from a small stock preserved at great cost in acknowledgment that all belongs to Him. People dishonor God by forgetting the Giver, glorifying human instrumentalities and natural causes, perverting His natural provisions into unnatural stimulants for perverted appetite that becloud the intellect and wear out the body, and by selfishness and indulgence bringing excess and want and polluting the earth by sin as did the inhabitants of the Noachic world.