Sahih Muslim | Book 35 | Chapter 21

Narrated by Abu Dharr
Abu Dharr reported that Allah's Messenger (may peace be upon him) was asked as to which words were the best. He said: Those for which Allah made a choice for His Angels and His servants (and the words are): "Hallowed be Allah and praise is due to Him.

Narrated by Abu Dharr
Abu Dharr reported that Allah's Messenger (may peace be upon him) said: Should I not inform you about the words liked most by Allah? I said: Allah's Messenger, do inform me about the words liked most by Allah. He said: Verily, the words liked most by Allah are: "hallowed be Allah and praise is due to Him.