Rebbe Nachman once said that everyone can see pity in the world. People do not want to be the objects of such pity and therefore pursue worldly things.
People see the pity others have for those who are hungry, thirsty or in serious trouble. They know how others react to a person who doesn’t have clothing or shoes. Therefore, they do not want to find themselves in such a predicament.
But one who understands clearly can also perceive the great pity we must have on souls in the World to Come. In the future life, there are souls which are literally naked. Still, it is impossible to show them any pity. If a person lacks clothing in this world, others can take up a collection and buy it for them. But such pity is impossible in the World to Come. The “clothes” one needs in that place are Torah and good deeds, (See Zohar II, 210a; Ramban on Genesis 49:33) and these cannot be given as charity. Spiritual garments must be earned through one’s own efforts.
The Rebbe discussed this another time, and said that in the World to Come, many people will be left outside. They will cry in a bitter voice, “Give us something to eat!” People will come to them and say, “Here is food and water. Eat! Drink!” But those outside will answer, “No! No! We cannot use such food. What we need is the food of Torah and G-dly service (mitzvot).”
Other people will be left outside, naked. They too will cry, “Give us something to cover ourselves with!” Again people will come to them and say, “Here is some clothing.” But to this too they will reply, “No! Such clothing is absolutely useless to us here. We need mitzvot and good deeds to cover ourselves with.”
The Rebbe then said, “Happy will be the person who is worthy of “eating” many chapters of mishna, drinking a number of Psalms, and clothing themselves with some good deeds.”
(Adapted from Sichos HaRan #23)