Sh. Muḥammad b. Ṣāliḥ al-ʿUthaymīn, may Allāh have mercy upon him, replied:

“It is not possible to delve into and discuss the Essence of Allāh (ذات الله) – the Almighty and Exalted – because attaining knowledge of the reality of Allāh’s Essence – the Almighty and Exalted – is impossible, and whoever desires that then he will fall into destruction and misery.

Yes, he should think and reflect on the Names of Allāh and His Attributes, just as He the Almighty and Exalted said:

{And to Allāh belongs the Most Beautiful Names so call upon Him by them, and keep away from those who deviate regarding His Names. They will be punished for what they used to do} [al-Aʿrāf: 180].”

Source: Fatāwá Nūr ʿalá al-Darb (1: 172, no. 125).