Imam Sadiq (a.s) said:
 الحَاجُّ والمُعتمِرُ وِفدُ اللهِ؛ إِن سَأَلوهُ أَعطَاهُم وإِن دَعَوهُ أَجابَهُم وإِن شَفَعوا شَفَّعَهُم وإِن سَكَتوا ابتَدَأَهُم ويَعوَّضُونَ بالدِّرهَمِ الفَ الفِ دِرهَم
The performers of Hajj and umrah are Allah's guests. If they ask, they will be given, if they pray, they will be answered, if they intercede, their intercession will be accepted, if they keep silent, they will be blessed, and they will be given a million dirhams for each one they have spent.See al-Wafi; Vol. 2