Musnad Ahmad 961:31

'Abd al-Razzaq narrated to us, Ma'mar informed us, from 'Asim ibn Abi al-Najud, from Abu Wa'il, from Mu'adh ibn Jabal, who said: I was with the Prophet, may God bless him and grant him peace, on a journey. One day, I became close to him while we were traveling, so I said: "O Prophet of God, inform me of a deed that will cause me to enter Paradise and distance me from the Fire." He said: "You have asked about something great, and it is easy for whoever God makes it easy for. You worship God and do not associate anything with Him, you establish the prayer, you give the zakat, you fast Ramadan, and you perform the pilgrimage to the House." Then he said: "Shall I not guide you to the gates of goodness? Fasting is a shield, charity extinguishes sin, and the prayer of a man in the middle of the night." Then he recited: {Their sides forsake their beds} [As-Sajdah: 16], until he reached: {they used to do} [As-Sajdah: 17]. Then he said: "Shall I not inform you of the head of the matter, its pillar, and the peak of its hump?" I said: "Yes, O Messenger of God." He said: "The head of the matter is Islam, its pillar is the prayer, and the peak of its hump is jihad." Then he said: "Shall I not inform you of the control of all of that?" I said to him: "Yes, O Prophet of God." So he took hold of his tongue and said: "Restrain this from yourself." I said: "O Messenger of God, are we to be held accountable for what we speak?" He said: "May your mother be bereaved of you, O Mu'adh! Does anything topple people into the Fire upon their faces—or he said: upon their noses—except the harvests of their tongues?"