Source of the berachos of a tzadik - heard from the Bostoner Rebbe

 I once asked the Bostoner Rebbe zt"l about how to understand that  Bilam's spiritual gifts were from the Sitra Acher. He replied with a chasidic story.  This is my best recollection of something I heard many years ago if anyone has a better version - please let us know!

There was once a very poor man who was crushed by his financial obligations which he had no  known rational path to settling. One day he was wandering in a dark forest where he met a man with a long white beard who immediately commented on his depression and sadness. When he explained about his overwhelming debt - the man said he would give him a beracha that would take care of the problem, When he returned home - all of a sudden  he became wealthy. He was very excited about his change of fortune - so he ran right away to tell his rebbe the good news. After he told his rebbe the whole story, his rebbe said "I want you to go back to that man and not only tell him you don't want his blessing but also that the reason is because it all came from the Sitra Acher." Of course he obeyed his rebbe. He found the man in the dark forest and delivered the message. The man replied,"I'll take it back on one condition - You need to take my comment back to your rebbe and repeat it exactly as I said it." He of course agreed to the condition. He returned to his rebbe with the following words, "All your power also comes from the Sitra Acher.  The Rebe screamed a horrible cry when he heard those words and he ran away and was never seen again,

 The rebbe said it is often difficult differentiating where the beracha is coming from.