Sayyiduna Anas (may Allah be pleased with him) states: The Prophet (peace and blessings be upon him) forbade sitting in the manner of iq'a' and tawarruk during the prayer.
Bazzar recorded it from his teacher Harun bin Sufyan, and I have not found anyone who mentions him; the rest of its narrators are the narrators of the Sahih.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الصلاة / 2467
Sayyiduna Samurah (may Allah be pleased with him) states: The Prophet (peace and blessings be upon him) forbade sitting in the manner of tawarruk and iq'a' during the prayer, and sitting on the heels with both feet upright.
Bazzar recorded it, and Tabarani recorded it in al-Mu'jam al-Awsat; its chain contains Sa'id bin Bashir, about whom there is criticism.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الصلاة / 2468