What is the ruling on habitually saying "by Allah upon you," and is it obligatory to fulfill the oath and does expiation become necessary?

The default rule is that it is reprehensible to ask people for things, except out of necessity. It is also reprehensible to ask by Allah, due to the pressure and embarrassment it causes. The phrase "by Allah upon you" (بالله عليك) has two uses:

1. As an oath: For example, if someone says, "I swear by Allah upon you." In this case, the one who took the oath is required to offer expiation if he does not fulfill his oath, and it is recommended for the one sworn upon to fulfill the oath.

2. As a request: For example, if someone says, "I ask you by Allah." This is not an oath, so no expiation is required. It is recommended for the one who is asked by Allah to respond, out of reverence for Allah, unless responding would cause hardship or difficulty.