What is the ruling of Islamic law on lying to a brother who does not pray or misses prayers, by claiming to have seen him in a bad dream, with the aim of encouraging him to pray?

Lying is one of the most heinous sins, and its ugliness and sinfulness increase when it is related to dreams. Abandoning prayer entirely is considered disbelief according to the preponderant opinion of scholars. It is advisable to supplicate frequently for the brother who does not pray, and to command him to pray and encourage him to do so. If that does not benefit and you expect that lying will make him enthusiastic about prayer, then it appears there is no objection to lying to him once, because lying may be permissible for praiseworthy purposes, and for every praiseworthy purpose that cannot be achieved except through it.