Sayyiduna Irbad bin Sariyah (may Allah be pleased with him) narrates: The Prophet (peace and blessings be upon him) said: "Whoever performs an obligatory prayer is entitled to a supplication that will be answered, and whoever completes the Qur'an is entitled to a supplication that will be answered."
Al-Tabarani recorded it; its chain contains a narrator, Abd al-Hamid bin Sulayman, who is da'if (weak).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب التفسير / 11712