Ibn 'Umar (May Allah be pleased with them) reported:
The Messenger of Allah (ﷺ) said, "(The superstructure of) Islam is based on five (pillars), testifying the fact that La ilaha illallah wa anna Muhammad-ar-Rasul-ullah [there is no true god except Allah, and Muhammad ((ﷺ)) is the Messenger of Allah], establishing As- Salat (the prayers), paying Zakat (poor due), the pilgrimage to the House [of Allah (Ka'bah)], and the Saum (fasting) during the month of Ramadan."[Al-Bukhari and Muslim].
App reference: Book 11, Hadith 1
Arabic/English book reference: Book 11, Hadith 1271