The word(s) "thereunto" appears 2 time(s) in 2 verse(s) in Quran in Abdullah Yusuf Ali translation.

(1) And if ye are in doubt as to what We have revealed from time to time to Our servant, then produce a Sura like thereunto; and call your witnesses or helpers (If there are any) besides Allah, if your (doubts) are true.

(سورة البقرة, Al-Baqara, Chapter #2, Verse #23)
(Arabic, Transliteration, Urdu (Ahmed Ali), Urdu (Jalandhry), Farsi, Yusuf Ali, Shakir, Picthal, Mohsin Khan, French, Spanish, Indonesian, Malay, German, Bosnian, Russian, Dutch, Italian, Portuguese, Tafsir - Jalal ad-Din, Tafsir - King Fahad Quran Complex)

(2) Still less can their knowledge comprehend the Hereafter: Nay, they are in doubt and uncertainty thereanent; nay, they are blind thereunto!

(سورة النمل, An-Naml, Chapter #27, Verse #66)
(Arabic, Transliteration, Urdu (Ahmed Ali), Urdu (Jalandhry), Farsi, Yusuf Ali, Shakir, Picthal, Mohsin Khan, French, Spanish, Indonesian, Malay, German, Bosnian, Russian, Dutch, Italian, Portuguese, Tafsir - Jalal ad-Din, Tafsir - King Fahad Quran Complex)