[Cash Remittances and Receipt by Card]

Answer: What appears is that this is permissible, because the increase is slight and added in exchange for the service; the benefit is equal for the sender and the receiver—there is neither oppressor nor oppressed—and none of the recognized forms of ribā is present in it. Even if we supposed it resembles a “loan that draws a benefit,” the lender here lends his money to the money-changer and requests a benefit, for which he pays a counter-value; thus the money has for its counter-value money like it, and the service has for its counter-value a service.
Likewise with the card: the bank is a depositary and a hireling. The bank takes a small amount in exchange for:
1. Safekeeping.
2. Providing automated teller machines in every city.
Even if we supposed that the bank takes what it takes without counter-value, that would still not be ribā, because the payer of funds—the one who lends—may remit to the borrower whatever discount he wishes; there is no harm upon him in that whatsoever, whether conditional or not. Likewise, a creditor may remit to a debtor and reduce whatever he wishes; this does not fall under the headings of ribā.
Ribā is only when the payer of funds—the lender—demands an increase; on that came the Qur’an and Sunnah. The Sunnah has also come with the like of what we mentioned regarding a debt the Banū al-Naḍīr had over the Muslims when the Prophet ,May Allah bless him and his family and grant them peace, commanded their expulsion from al-Madīnah. They said, “We have debts with people whose terms have not yet fallen due.” The Prophet, May Allah bless him and his family and grant them peace, said to them: “Reduce [the amount] and collect early.”
And Allah Most High has urged creditors to remit to debtors, saying: “And if someone is in hardship, then [let there be] postponement until [a time of] ease. And if you remit it as charity, it is better for you.” [Al-Baqarah:280]
Source: Min Thimār al-ʿIlm wa al-Ḥikmah vol.2