Jamieson, Fausset and Brown on John 12:35-36

35-36. Yet a little while is the light with you. Walk while ye have the light, &c.--Instead of answering their question, He warns them, with mingled majesty and tenderness, against trifling with their last brief opportunity, and entreats them to let in the Light while they have it in the midst of them, that they themselves might be "light in the Lord." In this case, all the clouds which hung around His Person and Mission would speedily be dispelled, while if they continued to hate the light, bootless were all His answers to their merely speculative or captious questions. (See on Lu 13:23).