Yes, the one who died in 19 AH and over whom ʿUmar led the funeral prayer was Khabbāb, the freedman of ʿUtbah ibn Ghazwān—himself a Companion and one of the Emigrants.

Mansūr related from Mujāhid:
“The first people to declare their Islam openly were the Messenger of Allah ﷺ, Abū Bakr, Khabbāb, Bilāl, Suhayb, and ʿAmmār.”

Ibn Isḥāq, however, records that Khabbāb embraced Islam after nineteen individuals, thereby completing the first twenty converts.

Ath-Thawrī narrated from Abū Isḥāq, from Abū Laylā al-Kindī:
ʿUmar said to Khabbāb, “Draw near; no one is more entitled to this seat than you—except ʿAmmār.” Khabbāb then uncovered his back to show him something—namely, the scars left by Quraysh’s torture. (1)

Abū al-Ḍuḥā narrated from Masrūq, from Khabbāb:
“I was a blacksmith in Mecca. I forged a sword for al-ʿĀṣ ibn Wāʾil. When I came to collect my payment he said, ‘I will not pay you until you disbelieve in Muhammad.’
“I replied, ‘I will never disbelieve in Muhammad ﷺ until you die and are raised again.’
“He retorted, ‘When I am resurrected I shall possess wealth (2), and then I will settle your due.’
“I reported this to the Messenger of Allah ﷺ, whereupon the verse was revealed: ‘Have you seen the one who rejects Our signs…’ [Maryam 19:78]. (3)

Including repeated chains, thirty-two hadiths are transmitted from Khabbāb, of which three are in