How to Obtain Two Qirats for Attending a Funeral

Is it necessary, in order to receive the full reward for attending a funeral, which is one qirat, to leave one’s own home or the home of the deceased, then pray over him, and then accompany him to the cemetery?
If he goes to the deceased’s home and joins them in escorting him to the mosque and then to the cemetery, he receives two qirats. If he only attends the prayer, he receives one qirat.