SAHIB AZ-ZAMAN & SAHIB AL-ASR
The word asr means time or time to come. It is a spiritual or eternal hour, which is hidden in material age. The material age is zaman. In other words, asr is batin and zaman is zahir. The Imam is the Lord of the spiritual as well as the material hours.
When the animosity of the enemies reached to its extreme during the dawr-i satr, the Imams were physically hidden from the eyes of their followers. The hujjats represented the Imams in different regions, who exhorted the Ismailis that they should obey the Lord of the Time (sahib az-asr or waliyul asr) without pronouncing the proper names of the Imams. This practice was thus in vogue among the neophytes during concealment period.