Abu Hurairah (May Allah be pleased with him) reported:
Messenger of Allah (ﷺ) said, "Allah says: 'I am just as My slave thinks of Me when he remembers Me.' By Allah! Allah is more pleased with the repentance of His slave than one of you who unexpectedly finds in the desert his lost camel. 'He who comes closer to Me one span, I come closer to him a cubit; and he who comes closer to Me a cubit, I come closer to him a fathom; and if he comes to Me walking, I come to him running".[Al-Bukhari and Muslim].
Arabic/English book reference: Book 1, Hadith 440