The word(s) "reassure" appears 4 time(s) in 4 verse(s) in Quran in Saheeh International translation.

(1) And Allah made it not except as [a sign of] good tidings for you and to reassure your hearts thereby. And victory is not except from Allah, the Exalted in Might, the Wise -

(سورة آل عمران, Aal-i-Imraan, Chapter #3, Verse #126)
(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) They said, "We wish to eat from it and let our hearts be reassured and know that you have been truthful to us and be among its witnesses."

(سورة المائدة, Al-Maaida, Chapter #5, Verse #113)
(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)

(3) And of the people is he who worships Allah on an edge. If he is touched by good, he is reassured by it; but if he is struck by trial, he turns on his face [to the other direction]. He has lost [this] world and the Hereafter. That is what is the manifest loss.

(سورة الحج, Al-Hajj, Chapter #22, Verse #11)
(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)

(4) [To the righteous it will be said], "O reassured soul,

(سورة الفجر, Al-Fajr, Chapter #89, Verse #27)
(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)