Musnad Ahmad 28:384

Bahz narrated to us, Sulayman—meaning Ibn al-Mughirah—narrated to us, from Thabit, a man from al-Sham narrated to us—and he used to follow ‘Abdullah ibn ‘Amr ibn al-‘As and listen [to him]—he said: I was with him when he met Nawf. Nawf said: It was mentioned to us that Allah the Exalted said to His angels: "Call My servants for Me." They said: "O Lord, how, while the seven heavens are between them and [You], and the Throne is above that?" He said: "When they say: 'There is no god but Allah,' they respond." ‘Abdullah ibn ‘Amr said to him: We prayed the Maghrib prayer, or another, with the Messenger of Allah (ﷺ). He said: A group of people, among whom I was, sat waiting for the next prayer. He said: He came toward us walking quickly—as if I am looking at him lifting his lower garment so that it would be swifter for him in walking—until he reached us. He said: "Will you not rejoice? That is your Lord who commanded the gate of the middle heaven—or he said: the gate of heaven—to be opened. Then He boasted of you to the angels, saying: 'Look at My servants; they have performed one of My rights, and then they are waiting to perform another right that they will perform.'"