Hadith.1353 - Abdullah ibn Sinan reports from Imam Jafar ibn Muhammad Al-Sadiq (as) who said:
"Recite 'Qul Huwa Allahu Ahad' (Surah Al-Ikhlas) and ‘Qul ya-ayyuhal kaafirun’ (Surah al-Kafirun) before you sleep, for they are a declaration of freedom from shirk (associating partners with Allah (swt)), and 'Qul Huwa Allahu Ahad' (Surah Al-Ikhlas) affirms the nature of the Lord (azj), Mighty and Majestic."