It is narrated from Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) used to recite Qul ya ayyuha al-kafirun and Qul huwa Allahu ahad in the two rak'ahs after the Maghrib prayer.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 10213