LORD, make me to know mine end, and the measure of my days, what it is: that I may know how frail I am.

Wesley's Notes

39:4 My end - Make me sensible of the shortness and uncertainly of life, and the near approach of death.

King James Translators' Notes

how...: or, what time I have here

Jamieson-Fausset-Brown Bible Commentary

4-7. Some take these words as those of fretting, but they are not essentially such. The tinge of discontent arises from the character of his suppressed emotions. But, addressing God, they are softened and subdued.

make me to know mine end-experimentally appreciate.

how frail I am-literally, "when I shall cease."

Matthew Henry's Concise Commentary

39:1-6 If an evil thought should arise in the mind, suppress it. Watchfulness in the habit, is the bridle upon the head; watchfulness in acts, is the hand upon the bridle. When not able to separate from wicked men, we should remember they will watch our words, and turn them, if they can, to our disadvantage. Sometimes it may be necessary to keep silence, even from good words; but in general we are wrong when backward to engage in edifying discourse. Impatience is a sin that has its cause within ourselves, and that is, musing; and its ill effects upon ourselves, and that is no less than burning. In our greatest health and prosperity, every man is altogether vanity, he cannot live long; he may die soon. This is an undoubted truth, but we are very unwilling to believe it. Therefore let us pray that God would enlighten our minds by his Holy Spirit, and fill our hearts with his grace, that we may be ready for death every day and hour.