Silsilat al-Ahadith al-Sahihah

Sayyiduna Amr bin Abasah (may Allah be pleased with him) narrates that the Noble Prophet (peace and blessings be upon him) said: "The night prayer is in sets of two rak‘ahs, and in the last part of the night, supplication is most readily accepted." I asked: Is it obligatory to supplicate in that part? He (peace and blessings be upon him) said: "No, no, (I am saying that) supplication is most readily accepted."