How did God expand the Prophet's breast, and did that happen twice at the hand of Gabriel?

Allah bestowed upon His prophets and messengers the blessing of prophethood, and He specially favored His Prophet Muhammad, peace be upon him, by expanding his breast (sharh sadr). This expansion of the breast encompasses great meanings, including: expanding his breast to Islam as a religion and a law, filling it with wisdom, knowledge, and faith, as evidenced by the incident of the splitting of his breast twice, removing worry and grief, bestowing upon him all the perfections his soul aspired to, informing him of Allah's pleasure with him, and that his breast became vast enough for Allah's legislative and predetermined decrees.