He was the last person to transmit from him.

Al-Bukhārī reports—through ʿAlī—that “he left behind roughly three hundred hadiths.”

Ibn al-Mubārak narrates from Sufyān:
“The preservers of knowledge among people are three: Ismāʿīl ibn Abī Khālid, ʿAbd al-Malik ibn Abī Sulaymān, and Yaḥyā ibn Saʿīd al-Anṣārī; and Ismāʿīl is the most knowledgeable regarding al-Shaʿbī and the firmest of them in reporting from him.”

Al-Walīd ibn ʿUtbah transmits from Marwān ibn Muʿāwiyah, who said: “Ismāʿīl used to be called ‘the Balance.’”

Mujālid relates on the authority of al-Shaʿbī: “Ibn Abī Khālid swallows up knowledge in great gulps.”

Abū Isḥāq, also citing al-Shaʿbī, said: “Ismāʿīl quaffs knowledge, draught after draught.”

Ibn al-Madīnī said: “I asked Yaḥyā al-Qaṭṭān, ‘Are the narrations you have taken from Ismāʿīl, from ʿĀmir, all sound?’ He replied, ‘Yes.’”

Al-Qaṭṭān likewise remarked: “Sufyān was highly impressed with him.”

ʿAbd Allāh ibn Aḥmad stated that his father said: “The soundest reports from al-Shaʿbī come through Ibn Abī Khālid; Ibn Abī Khālid drinks in knowledge as one drinks water.”

Yaḥyā ibn Maʿīn said: “Reliable.” The same appraisal was given by Ibn Mahdī and a number of others.

Yaʿqūb ibn Shaybah said: “Trustworthy, firmly established.”

Abū Ḥātim declared: “I would place no one ahead of him among al-Shaʿbī’s transmitters.”

Aḥmad ibn ʿAbd Allāh said: “A Kufan, a Follower, reliable.”

He was a righteous man who heard from five of the Prophet’s Companions, and he worked as a miller.

Muḥammad ibn ʿAbd Allāh ibn ʿAmmār al-Mawṣilī said: “An unimpeachable authority—if Ismāʿīl is not an authority, then who is?!”

I say: The scholars have unanimously affirmed his precision and the validity of citing him as evidence, and he was never branded with Shiʿite leanings or any other innovation—praise be to Allah.

A fair number of reports with lofty (short) chains from him have reached us, and his narrations in Ṣaḥīḥ al-Bukhārī are among the very highest there.