Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
Qurʾān Bukhārī Muslim Nasāʾī Abū Dāwūd Tirmidhī Ibn Mājah Mālik Aḥmad Dārimī Ḥākim Ibn Ḥibbān Ṭabarānī Nasāʾī's Kubrá Bayhaqī al-Luʾluʾ wa-al-Marjān Ibn Rajab's Fifty Riyāḍ al-Ṣāliḥīn Aḥmad's Zuhd Suyūṭī
quran:25:28 –

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

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!
القرآن:٢٥:٢٨ –

يَا وَيْلَتَىٰ لَيْتَنِي لَمْ أَتَّخِذْ فُلَانًا خَلِيلًا  

{يا وَيْلَتَى} ألفه عوض عن ياء الإضافة أي ويلتي، ومعناه هلكتي {ليتني لم أتخذ فلانا} أي أبيَّا {خليلا}.