The Highest Forms of Dhikr

Imām Ibn Taimiyyah, may Allāh have mercy on him, said:

The highest forms of dhikr of Allāh [remembering Him on the tongue and in the heart] are the prayer, followed by recitation [of the Qurʾān], followed by unrestricted dhikr.

Majmūʿ Al-Fatāwá, vol. 19, p. 121.