Complex sentence: Sheikh Juhany led his first salaat in Masjid Al Nabawi in the year 1998, he was appointed to lead salah in one of biggest Masjids in Washington but King Abdullah (when he was still crown prince) appointed him to lead Salaat in Masjid Al Nabawi.
Split into simpler sentences: Sheikh Juhany led his first salaat in Masjid Al Nabawi in the year 1998. He had been appointed to lead salah in one of the biggest Masjids in Washington but King Abdullah (when he was still crown prince) appointed him to lead Salaat in Masjid Al Nabawi.