Musar do Hioba 7:1

[In sum, one must know that he has come to this world only for a specified time, for Torah and mitzvoth, and that he is destined to return to the higher world to receive his reward. As it is written (Devarim 7:11): "which I command you today to do them," concerning which our sages of blessed memory have said: "Today to do them, and tomorrow to receive their reward." But, the yetzer hara entices a man in his youth, that he yet has many years to live, and, in truth, this is an error, as we have written above. For each day is given him by the Blessed Creator with exact accounting, as it is written (Job 7:1): "Does a man not have an allotted time upon the earth?" And he cannot exempt himself from this day in anticipation of the next day. A man in this world is like one who has come to sojourn in a distant land for a specific time, as it is written (Psalms 119:19): "I am a sojourner in the land; do not hide Your mitzvoth from me." He must pity each day, that it not go to waste.