The Prophet ﷺ reported that his Lord said, "Whoever remembers Me within himself, I remember him within Myself, and whoever remembers Me in a gathering of people, I remember him in a gathering greater and better than them."
حدثنا عفان حدثنا حماد يعني ابن سلمة عن عطاء بن السائب عن الأغر
عن النبي ﷺ فيما يحكي عن ربه عز وجل قال من ذكرني في نفسه ذكرته في نفسي ومن ذكرني في ملإ من الناس ذكرته في ملإ أكثر منهم وأطيب
Its isnad is sahih. Bukhari related it, 9/147, in the Book of Tawhid, chapter on what is mentioned about the Divine Essence and Attributes, and Muslim, 4/2061, no. 2675, in the Book of Remembrance and Supplication, chapter on the encouragement to remember Allah Almighty.