Midras Mazmur 119:80: Shemot Rabbah & Midrash Tehillim

Another interpretation: “This is the statute of the paschal offering” – that is what Scripture states: “Let my heart be whole in Your statutes” (Psalms 119:80). David said: ‘Master of the universe, when I engage in Your statutes, let the evil inclination not have permission to look at me, as it is stated: “Teach me, Lord, Your way, I will walk in Your truth” (Psalms 86:11). [Do this] so that the evil inclination will not mislead me, and I will be ashamed before the righteous. Moreover, because it misleads me, I neglect the words of the Torah, and when I come to exhibit my learning before You and those who are lesser than I, they respond and say to me that it is not so, and I am ashamed. Rather, make my heart one, so it will engage in Torah wholely.’ That is what is written: “Let my heart be whole in Your statutes, so that I will not be put to shame” (Psalms 119:80).
Another interpretation: “Let my heart be whole in Your statutes” – these are the statute of the paschal offering, and the statute of the red heifer. Why? It is because they are similar to one another. About this [the paschal offering] it is stated: “This is the statute of the paschal offering,” about that [the red heifer] it is stated: “This is the statute of the Torah” (Numbers 19:2),⁴This passage recounts the laws of the red heifer, whose ashes are used to purify a person from ritual impurity imparted by contact with a dead body. and you cannot know which statute is greater than the other. It is analogous to two similar noblewomen who were walking together and looked the same. Which of them is greater than the other? It is the one who is accompanied by the other to her home, and the other walks behind her. So, regarding the paschal offering “statute” is stated and regarding the [red] heifer “statute” is stated. Which is greater? It is the heifer, as those who partake of the paschal offering need it, as it is stated: “They shall take for the impure from the ashes of the burning of the purification” (Numbers 19:17). That is: “No foreigner shall eat of it.”⁵The midrash understands the foreigner to be a person who is ritually impure.

"Let the wicked be ashamed, for they have lied against me, etc." David said, "Even though the wicked may oppress me, I have not forsaken the Torah." Similarly, it is written (2 Samuel 21:22), "These four were born to the giant in Gath, etc." Even though they came upon me, I did not forsake the Torah, but rather (2 Samuel 22:1), "David spoke to the Lord the words of this song, etc." "Let those who fear You return to me and those who know Your testimonies." "Let my heart be sincere in Your statutes, etc." A pot in which I ate non-sacred food, I did not eat sacred food in it so that I would not be embarrassed. Therefore it is said (Psalms 119:80), "My heart is breached within me." And it is written (Psalms 119:80), "Let my heart be sincere in Your statutes." And it is written (Psalms 51:12), "Create in me a pure heart, O God." The heart is what causes a person to be ashamed of what he knows he has done and is ashamed of himself. Therefore it is said (Proverbs 14:10), "The heart knows its own bitterness, and a stranger does not share its joy." And the heart is what brings joy. And so David said, "Let my heart be sincere in Your statutes." And just as David asked for it, so did the Lord give him, as it is said (2 Samuel 22:36), "And You have given me Your shield of salvation, etc." Therefore it is said, "So that I will not be ashamed."