The Holy Spirit is one of the divine angels. According to traditions, one of the missions assigned to Him by Almighty God is to support the prophets and Imams (peace be upon them). This teaching, which is confirmed by numerous traditions, may serve as evidence for the infallibility of the prophets and Imams (peace be upon them). There are discussions about the essence of the Holy Spirit; at the same time, the extent to which the Holy Spirit accompanies the prophets and Imams (peace be upon them) and how this teaching can substantiate their infallibility are the main concerns of this writing. This paper, utilizing an analytical-narrative method and relying on authentic traditions, seeks to closely examine this issue. Based on the most significant findings of this research, it has been established that the prophets and Imams (peace be upon them) did not consistently rely on the Holy Spirit; therefore, the teaching of the Holy Spirit's companionship with the prophets and Imams (peace be upon them) is insufficient to prove their absolute infallibility, and other evidence must also be considered for this purpose.