What are the consequences of frequent swearing by Allah, intentionally and unintentionally, and what is its expiation? Is one expiation sufficient for all instances, and what about swearing not to take something from my sister and then taking it with her knowledge?

Frequent swearing is not befitting of a Muslim and is a sign of weak faith. A Muslim should strive to rid themselves of this bad habit. As for the oaths the questioner has broken, she must offer expiation for them to ensure her accountability is cleared. If she swore oaths concerning different things, then expiation is required for each oath. If the subject of the oath was one thing, and the oaths were repeated before breaking them, then only one expiation is required. Similarly, if the subject of the oath involved different things but the oath was one, then only one expiation is required. As for swearing an oath by tongue without intending its meaning, this is considered a vain oath (laghw al-yamin), for which no expiation is required. The expiation for an oath is: feeding ten poor persons or clothing them. If she cannot find them, then she must fast for three days.