Narrated `Abdullah bin `Amr:A bedouin came to the Prophet (ﷺ) and said, "O Allah's Messenger (ﷺ)! What are the biggest sins?: The Prophet (ﷺ) said, "To join others in worship with Allah." The bedouin said, "What is next?" The Prophet (ﷺ) said, "To be undutiful to one's parents." The bedouin said "What is next?" The Prophet (ﷺ) said "To take an oath 'Al-Ghamus." The bedouin said, "What is an oath 'Al-Ghamus'?" The Prophet (ﷺ) said, "The false oath through which one deprives a Muslim of his property (unjustly)

English translation · Sahih al-Bukhari