The friend of Allah, hadith qudsi
مَنْ عَادَى لِي وَلِيًّا فَقَدْ آذَنْتُهُ بِالْحَرْبِ، وَمَا تَقَرَّبَ إِلَيَّ عَبْدِي بِشَيْءٍ أَحَبَّ إِلَيَّ مِمَّا افْتَرَضْتُهُ عَلَيْهِ
Man 'ada li waliyyan fa-qad adhantuhu bi-l-harb, wa ma taqarraba ilayya 'abdi bi-shay'in ahabba ilayya mimma-ftaradtuhu 'alayh.
"Whoever takes a friend of Mine as an enemy, I declare war against him. My servant draws near to Me with nothing more beloved than the obligations I have placed upon him."
Narrated by Abu Hurayrah (hadith qudsi). Sahih al-Bukhari 6502 · Nawawi's Forty · #38
A short reflection
The hadith continues: voluntary worship brings you closer still, until Allah becomes the ear with which he hears and the eye with which he sees.