Where did Imam Ahmad place his hands during prayer, on his chest or below his navel, taking into consideration what was mentioned in the book "Al-Insaf" and what was narrated from him?

Placing the right hand over the left below the navel while standing in prayer is the well-known position in the Hanbali school of thought, as explicitly stated by Imam Ahmad. Others hold that the placement should be above the navel. Some have gone further, stating that both hands should be placed on the chest, a view favored by Sheikh Muhammad ibn Salih Al-Uthaymeen as the most probable, citing the hadith (definition) of Wa'il ibn Hujr as evidence. The jurisprudential narrations vary among these positions; some validate placing the hands below the navel, such as the hadith of Ali, while others indicate a disliking (karahah) of placing them on the chest, even though there are narrations supporting it.