وَيَقولونَ لَولا أُنزِلَ عَلَيهِ آيَةٌ مِن رَبِّهِ ۖ فَقُل إِنَّمَا الغَيبُ لِلَّهِ فَانتَظِروا إِنّي مَعَكُم مِنَ المُنتَظِرينَ

And they say, "Why is a sign not sent down to him from his Lord?" So say, "The unseen is only for Allah [to administer], so wait; indeed, I am with you among those who wait."