[2:138] The mark of God; and who has a better mark than God? And Him we worship.
Its meaning is 'They have been attached to the mark (ṣibgha) of God'. [The word 'mark'] is in the accusative because of the elision of the verb.
The allusion is to the fact that the admonitory lesson is in what the Real has set down, not in what the servant makes up. What mankind takes on will pass away in the end while what the Real has firmly established for [humankind] is the primordial nature (al-fi?ra), so his establishment of it is the lesson.
The hearts have a mark, the spirits have a mark, the innermost selves have a mark, and the outward selves have a mark. The mark of corporeal and outward selves (al-ashbāḥ wa'l-ẓawāhir) is in the traces of God granted success (āthār al-tawfīq) and the mark of the spirits and innermost selves (al-arwāḥ wa'l-sarāÌir) is in the lights of realization (anwār al-taḥqīq).