Commentary for Avodah Zarah 150:16

The Talmud asks whether Jews have to immerse a vessel if the non-Jew gave it to them as a pledge, which would ostensibly be returned to the non-Jew upon termination of the loan. Mar bar R. Ashi, one of the last amoraim, teaches that indeed his father did immerse such a vessel. However, he is not sure if this is because a vessel taken as a pledge is considered to be the property of the creditor (this is a question frequently asked in the Talmud). If this was true, then taking a pledge is just like buying. Or perhaps in this particular case R. Ashi assumed that the non-Jew was not going to take it back but in other cases, where the non-Jew might take it back, it would not be considered as belonging to the creditor and therefore the Jew would not have to immerse it.