Sunan Ibn Majah 2114
سنن ابن ماجه#2114SahihIt was narrated that Hammam heard Abu Hurairah saying that 'Abul-Qasim (ﷺ) said:"If anyone of you insists on fulfilling what he swore to (after learning that it is wrong) then it is more sinful before Allah than (breaking the oath for which) the expiation that has been enjoined upon him
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Al-AlbaniSahih
Muhammad Fouad Abd al-BaqiSahih
Zubair Ali ZaiSahih
In-book reference: 11:25