(Lo! now they) i.e. Akhnas Ibn Shurayq and his followers (fold up their breasts) conceal in their hearts their hatred and enmity for Muhammad (pbuh) (that they may hide from him) that they may hide from Muhammad (pbuh) their hatred and enmity by keeping his company and pretending to him that they love him. (At the very moment when they cover themselves with their clothing) at the moment they cover their heads with their clothes, (Allah knoweth that which they keep hidden) among themselves as well as that which they conceal in their hearts (and that which they proclaim) of fighting and antipathy; it is also said that this refers to that which they proclaim of love and keeping company. (Lo! He is Aware of what is in the breasts (of men)) whether it is good or evil.