Silsilat al-Ahadith al-Sahihah

It is narrated from Sayyiduna Abdur Rahman bin Shibl (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Indeed, traders are sinners." Someone said: O Messenger of Allah! Has Allah Almighty not made buying and selling lawful? He (peace and blessings be upon him) said: "Why not. But (the situation of these traders is that) when they speak, they lie, and they swear oaths (falsely), thus they become sinners."