Tafsir of Al-Mujadilah 58:18

يوم يبعثهم الله جميعا

On the Day when Allah will resurrect them all together; referring to the Day of Resurrection when He will gather them all together and leave none of them out,

فيحلفون له كما يحلفون لكم ويحسبون أنهم على شيء

then they will swear to Him as they swear to you. And they think that they have something. meaning, they will swear to Allah the Exalted and Most Honored that they were following the guidance and the correct path, just as they used to swear to the believers in this worldly life. Verily, those who live following on a certain path will most likely die while on it. Thus, they will be resurrected upon their path. The hypocrites will think that their vows will help them with Allah, just as they helped with the people, who were obliged to treat them as they pretended to be, Muslim. This is why Allah said,

ويحسبون أنهم على شيء

(And they think that they have something), meaning, on account of swearing to their Lord (that they used to be believers). Allah rebukes this idea of theirs;

أﻻ إنهم هم الكاذبون

Verily, they are liars! stressing that they are lying, Allah then said;