What is the ruling on adopting the Hadith of a trustworthy narrator who has been described as an innovator (bid'i), and does this ruling apply generally to every trustworthy innovator?

Scholars have differed on accepting the narration of an innovator (Mubtadi'), and the preponderant view is to accept his narration under certain conditions, including:

1. That his innovation does not render him an apostate.

2. That there is no reason to reject his hadith other than the innovation; rather, he should be known for piety and devoutness.

3. That he is not an obstinate preacher of his innovation.

4. That he does not narrate a deniable hadith that supports his innovation.