From the additional notes to Charles Spurgeon's The Treasury of David, on Psalm 119, verse 106.
I have sworn, and I will perform it, that I will keep thy righteous judgments.
I would now urge you to make a solemn surrender of yourself unto the service of God. Do not only form such a purpose in your heart, but expressly declare it in the Divine presence. Such solemnity in the manner of doing it is certainly very reasonable in the nature of things; and sure it is highly expedient, for binding to the Lord such a treacherous heart, as we know our own to be. It will be pleasant to reflect upon it as done at such and such a time, with such and such circumstances of place and method, which may serve to strike the memory and the conscience. The sense of the vows of God which are upon you will strengthen you in an hour of temptation; and the recollection may encourage your humble boldness and freedom in applying to him under the character and relation of your covenant God and Father, as future exigencies may require.
Do it therefore, but do it deliberately. Consider what it is that you are to do: and consider how reasonable it is that it should be done, and done cordially and cheerfully, "not by constraint, but willingly"; for in this sense, and every other, "God loves a cheerful giver."...
Let me remind you that this surrender must be perpetual. You must give yourself up to God in such a manner, as never more to pretend to be your own; for the rights of God are like his nature, eternal and immutable; and with regard to his rational creatures, are the same yesterday, today, and forever.
I would further advise and urge, that this dedication may be made with all possible solemnity. Do it in express words. And perhaps it may be in many cases most expedient, as many pious divines have recommended, to do it in writing. Set your hand and seal to it, "that on such a day of such a month and year, and at such a place, on full consideration and serious reflection, you came to this happy resolution, that whatever others might do, you would serve the Lord." — PhilipDoddridge (1702-1751) in "The Rise and Progress of Religion in the Soul."