Musnad Ahmad 28:570

Yahya ibn Ishaq narrated to us, Ibn Lahi'ah informed us, from Darraj Abu al-Samh, from Isa ibn Hilal, from Abdullah ibn Amr ibn al-As, who said: The Prophet, may Allah bless him and grant him peace, said: "Indeed, the souls of the believers meet at a distance of a day and a night's journey, even though neither of them has seen the other."