Beware... the leaven of the Pharisees and Sadducees...

"Does a good man forfeit his holy comfort, by making his graces, or performances, or lively frames, his ground of right to trust in Jesus for salvation? He should hence learn the need that he has, to be daily exercising himself in mortifying the legal spirit, which remains in him. It is this, that prompts him to make his graces and duties, his warrant to renew his actings of trust in the Saviour; and thereby, to forfeit the comfort of his soul. Next to unbelief itself, his legal temper is, perhaps, the worst enemy of his pure consolation. It is a secret and subtle foe, that seems to intend him a kindness; whilst it is always putting him, upon seeking for some good qualifications in himself, on the ground of which, he may trust that God loveth him, and that Christ saveth him. Let him, therefore, if he would retain spiritual comfort, be diligent in mortifying his sell-righteous spirit; and know that, the way to conquer and destroy it, is, by faith, to bring daily into his conscience a better hope, from a better righteousness than that of the law. All the spiritual distress of the exercised Christian, may be traced to a legal spirit in him. He seldom wants comfort, but by looking less or more to his own righteousness, instead of looking off, to the consummate righteousness of Jesus Christ. Believer, it is not sufficient, in order to maintain spiritual comfort, that thou dost not rely on thy graces and performances, for a title to eternal life. Thou must not presume to rely on them, for even so much as a right to trust in Christ: thou must not make them, the smallest part of thy warrant, to renew thy exercise of confidence in him."
John Colquhoun, Treatise on Spiritual Comfort - pp 115-117

Footnote:
... all true and solid peace is built upon justification by the blood of Christ, so it can only be maintained by the daily exercise of faith, in this comfortable doctrine. " Being justified by faith, we have peace with God, through our Lord Jesus Christ." Rom v. 1. But so far as the legal temper prevails, their peace is set upon another foundation; is built upon their enlargements in duty, their frames, and attainments in religion; and therefore must be unstable as water (The Evangelical Preacher, vol. iii. p. 199.)