What is the ruling on swearing by Allah concerning something of which a person has no knowledge, and is it permissible to swear by something in the unseen with certainty that it will not happen?

The one who takes an oath falls into several categories: If he knows the truth of what he is swearing to, then he is righteous and nothing is upon him. If he knows the falsity of his oath, then he is sinful and has committed a major sin. As for one who swears based on the strong probability (ghalabat al-dhann) that he is truthful, then nothing is upon him, even if the matter turns out to be contrary to what he swore, because "the strong probability is treated in rulings as certainty." However, one who swears recklessly about something he knows nothing about is sinful. As an example of swearing based on strong probability, Allah the Almighty says: "By Allah, there is no household between its two lava fields poorer than mine." Here, the man swore based on his strong probability. Similarly, if one swears that a person will arrive based on his presumption, and then the person does not arrive, there is no sin upon him and no expiation. A Muslim should not hasten to swear an oath except when necessary and with certainty. If he swears based on his strong probability and it turns out to be otherwise, there is no sin upon him, and it falls under the category of a thoughtless oath (laghw al-yameen). However, swearing a deliberate false oath is a sin and does not entail expiation.