It is a strong corroborating report for the hadith. And Allah knows best.

“Qazzaḥahu,” with the zāy doubled, is derived from qizaḥ, meaning spices. One says, “I qazzaḥtu the pot,” when one puts spices into it.

“Malaḥahu,” with the lām ungeminated: that is, he put into it a quantity of salt sufficient to improve it. One says, “I malaḥtu the pot,” with the lām ungeminated; whereas “amlaḥtuhā” and “mallaḥtuhā” mean that one put in so much salt that it spoiled.

383 — “Part of the Sunnah in prayer is to rest your buttocks upon your heels between the two prostrations.”

Al-Ṭabarānī narrated it in al-Muʿjam al-Kabīr (3/106/1): Aḥmad ibn al-Naḍr al-ʿAskarī narrated to us; ʿAbd al-Raḥmān ibn ʿUbayd Allāh al-Ḥalabī narrated to me; Sufyān ibn ʿUyaynah informed us, from ʿAbd al-Karīm, from Ṭāwūs, from Ibn ʿAbbās—may Allah be pleased with him—who mentioned it.

I say: This is an authentic chain if this ʿAbd al-Karīm is Ibn Mālik al-Jazarī al-Ḥarrānī. But if he is Ibn Abī al-Mukhāriq al-Muʿallim al-Baṣrī, then he is weak. I have no evidence before me by which to give preference to either possibility, for both of them narrated from Ṭāwūs, and Ibn ʿUyaynah narrated from each of them.

Nevertheless, the hadith is authentic in any case, for Ibn ʿUyaynah also narrated it from Ibrāhīm ibn Maysarah, from Ṭāwūs, through the same route, with similar wording.