Sayyidah Aishah Siddiqah (may Allah be pleased with her) narrates this saying of the Prophet (peace and blessings be upon him): "Whoever believes in Allah Almighty and the Last Day should not harm his neighbour; and whoever believes in Allah Almighty and the Last Day should speak good or else remain silent; and whoever believes in Allah Almighty and the Last Day should honour his guest."
Ahmad recorded it, and its narrators are thiqat (trustworthy).