وَقَالُوا لَن نُّؤْمِنَ لَكَ حَتَّىٰ تَفْجُرَ لَنَا مِنَ الْأَرْضِ يَنبُوعًا
“And they say, 'We will not believe you until you break open for us from the ground a spring.”
This ayah is part of the passage in Surah al-Isra (17:90-93) listing the specific miracles the Quraysh demanded before they would believe -- described at this event.