Translation:

127. Whenever there cometh down a Surah they look at each other (saying) "doth anyone see you?" Then they turn aside: Allah hath turned their hearts (from the light); for they are a people that understand not.

Notes (Tafseer)

1378. Even the Unbelievers, in their heart and conscience, feel uncomfortable when they turn away from Faith and Truth, and therefore their turning aside is figured by furtive glances, such as we may suppose literally to have been cast by the Hypocrites in the assemblies of the Holy Prophet. Then they slink away, feeling superior in their minds. And yet, if they only knew it, their contumacy deprives them of Allah's grace and light. They are turning Grace away, and when Allah withdraws it altogether, they perish utterly.