What is the opinion regarding the Middle Prayer being Isha' (night prayer)?

Primary text

One view suggests the Middle Prayer is Isha'. This is based on narrations that the heaviest prayers for the hypocrites are the dawn and the late night prayer (Isha'), and the narration that the Prophet (peace be upon him) delayed Isha' significantly one night, stating he would pray it at that time if not for hardship on his community.