Musnad Ahmad 33:359

Abu Amir narrated to us, Ibn Abi Dhi'b narrated to us, from Abd al-Rahman ibn 'Ata', from Abd al-Malik ibn Jabir ibn 'Atik, from Jabir ibn Abdullah, that the Prophet (peace and blessings of Allah be upon him) said: "Whoever speaks of a matter in a gathering, then looks around, it is a trust."