Even though Cure-All Clinic couldn't be considered big, it definitely wasn’t small. Besides the main shop, there were still two patient rooms on the first floor. On the second floor, there was a guest room and two cultivation rooms.
After Mo Wuji entered a cultivation room, he formed seals on the door. Thereafter, he took out that rental agreement.
That white-haired old man was a God King, so it wasn’t unusual that he wasn’t able to see through the trap within the jade letter. Even if his sea of consciousness was any stronger, it couldn't be compared to a God King. However, this gave him a reminder that even if he didn't notice anything wrong, it didn't mean that it was actually so.
An additional condition had appeared in the jade letter. This should be due to a concealment seal. The reason why he didn't see through it previously shouldn't be because his Array Dao was inferior to the white-haired elder, but because his spiritual will was far weaker.