Musar su Salmi 119:19

What we learn from all this is how careful we must be when we reside in a land that enjoys G–d's daily personal supervision. We must conduct ourselves submissively vis a vis G–d. King David expressed this sentiment when he said גר אנכי בארץ , "I am merely a stranger in the land (of Israel)" (Psalms 119,19) David considered himself as at most possessing the status of a stranger in that land. When G–d told Abraham in Genesis 15,13: "Know that your descendants will be strangers in a land that is not theirs,” we must ask why He added the words "in a land that is not theirs?" Is it not clear that one can only be a stranger in a land that one does not own? Rashi addresses this problem and says that this expression includes the times when Abraham's descendants would also at times be strangers in countries other than the land of Egypt, during the 400 years which start with the birth of Isaac. Other commentators see in this expression an allusion to the fact that Israel would reside in Goshen, i.e. not Egypt proper, the expression לא להם, referring to the Egyptians who did not "own" Goshen, seeing it had been given to Sarah by Pharaoh. Alternately, it could refer to the resettlement policy of the Egyptians which Joseph had initiated in Genesis 47,21, where Rashi explains that as a result none of the Egyptians themselves had a real claim to the land they were settled on It is clear in our context, that Abraham's descendants, i.e. Israel, were meant to become strangers and subsequently slaves to Pharaoh in Egypt. At a later stage in their history they would become strangers in their own country. This is why G–d emphasized that during these first four hundred years or part thereof they would be strangers in someone else's country. Afterwards they would be strangers just as David described himself as a stranger in ארץ ישראל.

[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.

The analogue is self-explanatory. A man's soul, when it descends to the earth is an absolute sojourner [not a "settler" as he is in heaven, (as it is written (Psalms 39:13): "I am a sojourner with You, a settler, like all of my forefathers")], who has come to sojourn here to attain Torah and mitzvoth. For in heaven he can earn nothing, and he has been given an allotted time for this, to return afterwards to its source above and to be bound up there in the bond of life with the L-rd his G-d. And he must reflect upon every day and every hour from the day he becomes a man to ascertain that his sojourn in this world not be in vain. This is the intent of (Psalms 119:19): "I am a sojourner in the land; do not hide Your mitzvoth from me." And the man who answers "I am only twenty, or thirty and I have time" is like the idle sage mentioned above.]