Riyad-us-Saliheen 1013
Anas (May Allah be pleased with him) reported: A man said: "O Messenger of Allah! I love Surat-Al-Ikhlas [Say: He is Allah, (the) One]." He (PBUH) said, "Your love for it will admit you to Jannah."
[At-Tirmidhi]
Some scholars have highlighted the eminence of Surat Al-Ikhlas by saying that it comprises the whole discipline of Tauhid. This Surat deals with Tauhid. Many other reasons have also been given for its great eminence by Muslim scholars.