He passed by the Prophet ﷺ while I was supplicating with my finger, and he said, "One, One," pointing with the index finger.
مر على النبي ﷺ وأنا أدعو بإصبعي فقال: أحد أحد وأشار بالسبابة.
Abu Dawud (1499) and Nasai (1273) both narrated it through Abu Muawiya, who said, Amash narrated to us, from Abu Salih, from Saad bin Abu Waqqas, and he related it. Its chain of transmission is sahih.As for his saying "one, one," it means gesture with one finger, in keeping with the oneness of Allah.