Sayyiduna Abu Hurayrah (may Allah be pleased with him) narrates from the Prophet (peace and blessings be upon him) that: "The greatest liars among people are al-sabbaghun and al-sawwaghun."
This is the preserved (mahfuz) version: the hadith of Hammam from Farqad. Some erred in it from Hammam, saying: from him, from Qatadah, from Yazid; and others said: from him, from Qatadah, from Anas; both of these are batil (false). It has also been narrated through another route from Abu Hurayrah, and it is said: from Abu Sa'id, as a marfu' (Prophetic) report.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الشهادات / 21178
Yahya bin Musa al-Balkhi (may Allah have mercy on him) said: I asked Abu Ubayd al-Qasim bin Sallam (may Allah have mercy on him) about its explanation, and he said: al-sabbagh is the person who adds words to speech in order to embellish it, and al-sa'igh is the person who narrates something baseless.
Al-Shaykh (may Allah have mercy on him) said: This is what is narrated from him. It is also possible that what is meant is the one who works with his hands, which is explicit in the version narrated from Abu Sa'id; he was described as a liar, and Allah knows best, because of his many false promises while knowing that he will not keep them. The soundness of this hadith is doubtful.
Imam al-Shafi'i (may Allah have mercy on him) mentioned the testimony of one who takes a fee for doing good, and the proof that this is permissible has already passed in the Book of Hire and elsewhere. As for anyone in a state because of which his testimony is rejected, Imam al-Shafi'i (may Allah have mercy on him) said: His testimony is rejected only while he remains in that state; when he gives it up and repents, his testimony is accepted.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الشهادات / 21179