In this same Hadith, Alqama ibn Waqqas1 heard Umar and reported it.
• Umar heard the Prophet ﷺ.
• Alqama heard Umar.
Alqama is also a narrator. He heard this Hadith from Umar, not directly from the Prophet ﷺ.
This is one part of the sanad of this Hadith in Sahih al-Bukhari. (Sahih al-Bukhari: 1)
1. Ibn (بن): In an Arabic name, it means “son of”; Alqama ibn Waqqas means Alqama, son of Waqqas.