What is the expiation for the oath of a person who swore by Allah Almighty that he would pay a sum of ten thousand Saudi Riyals if he resumed looking at immodest pictures, and he has done so twice?

Repentance erases what came before it. Anyone who finds illicit images on their device must immediately avert their gaze, destroy them, and take precautions for the future. If someone swore to pay a certain amount if they saw such images, and then saw them, they must fulfill their oath; otherwise, an expiation for a broken oath (kaffarat yameen) becomes obligatory: feeding ten poor persons, or clothing them, or emancipating a slave. If unable to do so, then fasting for three days. If the oath is repeated with a formula of repetition, the expiation multiplies with each instance of breaking it.