Let my heart be sound ... - Hebrew, “Be perfect.” See the notes at Job 1:1. The Septuagint here is “immaculate,” ἄμωμος amōmos. So the Latin Vulgate. It is the expression of a desire that the heart might be pure; that there might be no improper attachment for other objects; that there might be no defect of love to God.
That I be not ashamed - See the notes at Psalms 119:6. A man has no occasion to be ashamed of a pure heart; and that which can alone keep us from being ultimately ashamed is sincerity, uprightness, and purity in the service of God.