Since The Substance Is There

If a tailor does blacksmithing, his beard will burn. He should do his own work. Or, he should come to the blacksmith and say, "O blacksmith, teach me blacksmithing," So that he may teach him blacksmithing. Then his beard will not burn, just as the smith's beard does not burn.
If you spend a hundred dirhems on food, but you don't add two cents-worth of salt, it will be nothing. It won't go down the throat. If you do add two cents-worth of salt, wathever you pick up will be salty.
Someone may say "salt", but its meaning and state won't be there. until it is, ascetic discipline will have no result. Rather, it will produce darkness, since the substance is not there.
The Prophet by no means came to give news to him who doesn't have it. Rather, to the one who has it, he said, "You also have it." A good-news giver and a warner. it will become apparent who has it and who doesn't.

Shams
"Me & Rumi" William C. Chittick - Following Muhammad - 56