Complex sentence: Phelps, himself, was called to the stand by Daniel Webster, acting on behalf of the will's executors, and showed extreme composure, claiming he had no recollections of ever feeling persecuted.
Split into simpler sentences: Phelps, himself, was called to the stand by Daniel Webster, acting on behalf of the will's executors. During his testimony, Phelps showed extreme composure and claimed he had no recollections of ever feeling persecuted.