Psalms 51:10 - Coke's Commentary on the Holy Bible

Create in me a clean heart— A clean heart, is a heart free from those impure and disordered passions of which David had too fatally felt the effects, and in possession and under the influence of those sacred dispositions of piety, holiness, and virtue, in which the moral rectitude and purity of the mind consists. A right spirit, is more properly a firm, constant, determined spirit. It implies such a resolution and firmness of soul, as through grace should effectually secure him against the power of all future temptations. See 2 Corinthians 5:17. Ephesians 2:10. Mudge renders it, A spirit firmly steady.