It is narrated from Sayyiduna Samurah bin Jundab (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) forbade "doing iq'a' in prayer".
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2739
It is narrated from Sayyiduna Anas (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) forbade "iq'a' and tawarruk in prayer".
Only Yahya bin Ishaq al-Saylahini narrated it from Hammad bin Salamah. It has also been reported from him from Hammad and Bahr bin Kathir from Qatadah from Anas, and the first narration is more authentic.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2740
It is narrated from Sayyiduna Abu Hurayrah (may Allah be pleased with him): "The Messenger of Allah (peace and blessings be upon him) commanded me to do three things and forbade me from three things. He (peace and blessings be upon him) commanded me to fast three days every month, to sleep only after praying witr, and to pray the two rak'ahs of Duha (forenoon prayer); and he forbade me from glancing around in prayer like a fox, sitting like a monkey, and pecking like a rooster."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2741
It is narrated from Sayyiduna Ali (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "O Ali!" and in it, it is also mentioned that he (peace and blessings be upon him) said: "Do not do iq'a' between the two prostrations."
Al-Harith al-A'war is not used as evidence, and likewise Layth bin Abi Sulaym; and the hadith of Ibn Abbas and Ibn Umar is sahih (authentic).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2742
(a) It is reported from Abu Ubaydah that iq'a' means that a person places his buttocks on the ground, keeps his shins upright and places both his hands on the ground.
(b) In another place he defines it thus: that a person sits on his buttocks in such a way that his thighs are raised (like a beast of prey and a dog).
(c) The Shaykh, Imam al-Bayhaqi (may Allah have mercy on him), said: This type of iq'a' is not the one we have reported in the narrations of Abdullah bin Abbas and Abdullah bin Umar (may Allah be pleased with them both); rather, the iq'a' here is what has been forbidden, and what is in the narrations reported from Ibn Abbas and Ibn Umar (may Allah be pleased with them both) is Sunnah. As for the hadith of Abu al-Jawza', which he narrates from Aishah (may Allah be pleased with her), that the Prophet (peace and blessings be upon him) used to forbid "the squatting of Satan" and he (peace and blessings be upon him) used to lay his left leg down and keep his right leg upright, there is the possibility that he (peace and blessings be upon him) was in the final tashahhud, so it does not contradict the narrations we have mentioned from Ibn Abbas and Ibn Umar (may Allah be pleased with them both) about the sitting between the two prostrations. And Allah knows best.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2743