1)
Why does he request "Yehi Libi Samim"?
1.
Radak: Help me that my heart be complete in Your Chukim, so I will not be ashamed.
2.
Malbim: Even though I will speak about Pikudim, which have reasons, the heart can still question Chukim, whose reason is not known. If his heart is not complete in Emunah, he will be ashamed to guard the Chukim that Nochrim challenge.
