[4:81] They say, Obedience; but when they sally forth from you, a party of them harbor other than what they say. God writes down what they harbor. So turn away from them, rely on God, and God suffices as a Guardian.
It means that when they come to you, they surrender in your witnessing (mushāhada), but when they leave, the light of your approach (iqbāl) is cut off and they return to darknesses, just as they say:
Whenever he repents
he returns to his ignorance,
just as the one who is feeble
suffers a relapse.