"There are those who are ready to be fully assured; there are others to whom it will be death to talk of it. There is a great difference between presumption and full assurance. Full assurance is reasonable: it is based on solid ground. Presumption takes for granted, and with brazen face pronounces that to be its own to which it has no right whatever. Beware, I pray thee, of presuming that thou art saved. If with thy heart thou dost trust in Jesus, then art thou saved; but if thou merely sayest, "I trust in Jesus," it doth not save thee. If thy heart be renewed, if thou shalt hate the things that thou didst once love, and love the things that thou didst once hate; if thou hast really repented; if there be a thorough change of mind in thee; if thou be born again, then hast thou reason to rejoice: but if there be no vital change, no inward godliness; if there be no love to God, no prayer, no work of the Holy Spirit, then thy saying, "I am saved," is but thine own assertion, and it may delude, but it will not deliver thee. Our prayer ought to be, "Oh that thou wouldest bless me indeed, with real faith, with real salvation, with the trust in Jesus that is the essential of faith; not with the conceit that begets credulity. God preserve us from imaginary blessings!… Nothing will stand the trial but this, “Do you renounce all confidence in everything but the finished work of Jesus, and do you come to Christ to be reconciled in him to God?” If you do not, then your dreams, and visions, and thoughts, are nothing but dreams, and visions, and thoughts, and will not serve you when you most need them."
–Charles Spurgeon, "The Prayer of Jabez," Spurgeon's Sermons, Volume 17: 1881. (Grand Rapids, MI: Christian Classics Ethereal Library, 2002), pp. 265-266.