3,536. If the Location of Second Tithe Is Revealed in a Dream
Hilchos Maaser Sheini and Neta Revai 6:5
Let’s say that someone loses the ability to speak. If he’s asked if his second tithe is in a particular place and he nods, he is to be tested three times (i.e., by asking three different questions to ensure that he is communicating), just like such a person is tested when giving his wife a divorce. Once it has been established that he understands and replies appropriately, his communication is effective.
Hilchos Maaser Sheini and Neta Revai 6:6
If someone sees in a dream that his father’s second tithe – which he has been looking for – is in a certain place, even if he finds money there, it’s not second tithe. This is because messages communicated in dreams have no halachic weight.