It is narrated from Sayyiduna Ibn Umar (may Allah be pleased with them both) that there was a man from the Ansar who used to be deceived by people in trade, and he also had a stammer in his speech. He complained to the Prophet (peace and blessings be upon him) about the deception he faced. The Prophet (peace and blessings be upon him) said: When you make a sale, say: "There is no deception in this sale." Sayyiduna Ibn Umar (may Allah be pleased with them both) says: By Allah, it seems as if I am still hearing him saying "La khilabah" while making a sale, and his tongue is faltering.
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 6134
Hadith Gradingحکم دارالسلام:حديث صحيح، وهذا إسناد حسن .