Which Surah is equivalent to half of the Qur'an?

No authentic prophetic tradition (hadith) has been reported from the Prophet, peace and blessings be upon him, stating that Surat Az-Zalzalah (The Earthquake) is equivalent to half of the Qur’an. The narrations mentioned in this regard are weak or denounced (munkar). Some of the early Imams of the Salaf (pious predecessors) held the view that Surat Az-Zalzalah is equivalent to half of the Qur’an in terms of the meanings and objectives conveyed by the Qur’an, but this does not mean it is equivalent to half of the Qur’an in terms of reward and recompense.