Surah Al-Furqan 25:28

يَـٰوَيْلَتَىٰ لَيْتَنِى لَمْ أَتَّخِذْ فُلَانًا خَلِيلًا

Oh, woe to me! I wish I had not taken that one as a friend.

Translation: Saheeh International

Tafsir

O woe to me! yā waylatā the final alif stands in place of the first person singular possessive yā’ yā waylatī meaning ‘alas for my destruction!’ Would that I had not taken so and so in other words that Ubayy as friend!

Excerpt from Tafsir al-Jalalayn, commentary on 25:28, via Quran.com. The reader has the full commentary and 9 more tafsirs.