Al-Kahf 18:70

Qala fa-ini ittabaAAtanee falatas-alnee AAan shay-in hatta ohditha lakaminhu thikra

He said, "Then if you follow me, do not ask me about anything until I make to you about it mention [i.e., explanation]."

He said, “Well, if you follow me, do not ask me about anything unless I myself start telling you about it.”