Ikrimah bin Khalid Makhzumi narrates: A man asked Sayyiduna Abdullah bin Umar (may Allah be pleased with them): Why do you not participate in battles? He replied: I heard the Prophet Muhammad (peace be upon him) say:“Islam is built upon five things: Bearing witness that there is no god but Allah, establishing prayer, giving zakat, fasting in Ramadan, and performing Hajj to the House of Allah.”