Num 15:17-19
7 GOD spoke to Moses: 18 "Speak to the People of Israel. Tell them, When you enter the land into which I'm bringing you, 19 and you eat the food of that country, set some aside as an offering for GOD.

The main point was not to be sure that you GIVE something to God but that you are thankful to God for what you’ve been given. Because everything is from Him and that’s not what I see happening today.