One of the main source of dispute during his lifetime and continuing since then , is Mirza Ghulam Ahmad 's use of the terms â Nabiâ ( prophet ) and â Rasoolâ ( messenger ) when referring to himself . One of the main source of dispute during his lifetime and continuing since then , is Mirza Ghulam Ahmadâ s use of the terms â Nabiâ ( prophet ) and â Rasoolâ ( messenger ) when referring to himself .