Abu Hurairah (May Allah be pleased with him) reported:
Messenger of Allah (ﷺ) said, "Allah the Exalted has said: 'I will declare war against him who shows hostility to a pious worshipper of Mine. And the most beloved thing with which My slave comes nearer to Me is what I have enjoined upon him; and My slave keeps on coming closer to Me through performing Nawafil (prayer or doing extra deeds besides what is obligatory) till I love him. When I love him I become his hearing with which he hears, his seeing with which he sees, his hand with which he strikes, and his leg with which he walks; and if he asks (something) from Me, I give him, and if he asks My Protection (refuge), I protect him".[Al- Bukhari].
Arabic/English book reference: Book 1, Hadith 95