Thus did we raise them up that they might question each other. Spake a speaker amongst them, 'How long have ye tarried?' They said, 'We have tarried a day or part of a day.' They said, 'Your Lord knows best your tarrying; so send one of you with this coin of yours to the city, and let him look which of them has purest food, and let him bring you provision thereof; and let him be subtle and not let any one perceive you.