Speak to the children of Israel, and have them take for Me an offering; from every person whose heart inspires him to generosity, you shall take My offering (Shemos 25:2).

Rashi explains: "and have them take for Me" means dedicated to My name (Midrash Tanchuma).

If you were asked to give a donation to help rebuild the 3rd Temple wouldn't you give with a full heart and for the sake of the mitzva? Why does Chazal need to tell us that the giving of the money for the mishkan needed to be with such pure intentions?

Rav Henach Leibowitz learns that even when the evil inclination cannot stop us from doing a mitzva he can corrupt our intentions and degrade our service to our Creator.

We need to be constantly on guard that we do not perform the mitzvoth for honor, prestige, or other side motivations. Since we are spending much time and energy to do the mitzvoth anyway, it makes sense that we should work on purifying our motives. One mitzva done with a truly pure heart can upgrade and change the quality of our entire being.

Application: Choose one mitzva that you are going to do with absolute purity.

Give 10 quick answers to the following sentence stem: If I could do this mitzva with absolute purity, I would ...