What is "al-tahalum" (sexual dreaming), and is it forbidden, or is there any fault in it?

"Tahallum" (feigning forbearance) is the act of displaying forbearance and patience to people, even though one does not truly possess these qualities. If this is done with the intention of deceiving and misleading to obtain what one is not rightfully entitled to, then it is impermissible. However, if it is for the purpose of training oneself in these good qualities, then it is correct and desirable.