Musnad Ahmed: Hadith 2162

Pray to your Lord and ask Him to make asSafa gold for us, and we will believe in you. He said: “Will you do that?” They said: Yes. So he prayed, and Jibreel came to him and said: “Your Lord, may He be glorified and exalted, conveys greetings of salam to you and says to you: 'If you wish, as-Safa will become gold for them, then whoever among them disbelieves after that, I will punish him in a way that I have never punished anyone in the worlds, Or if you wish, I will open for them the gate of repentance and mercy.” He said: “Rather the gate of repentance and mercy.”