The hadith of the pillars
Sahih al-Bukhari (8) and Sahih Muslim (16) report from Ibn Umar (may Allah be pleased with them both) that the Prophet ﷺ said Islam is built on five things. They are the testimony that there is no god but Allah and that Muhammad is the messenger of Allah, establishing the prayer, giving zakah, performing hajj to the House, and fasting in Ramadan. Some narrations in Sahih Muslim mention fasting before hajj.
A pillar holds up a building. In the same way, these five acts support a Muslim's faith and daily conduct.