Ling Yun left Yao Rou's house at midnight with a desire to see his precious Shichiyou Herb. Hence, he used his ability to sprint towards the small river at lightning speed. If Yao Rou was to see his speed now, she would definitely not have commented on his speed just now.
In the night, Ling Yun moved quietly like an oversized owl and within the radius of 20 meters, he was practically invisible to the human eye. The distance between the Shichiyou Herb and Yao Rou's house was about 20 kilometers but he reached the place in five minutes.
Slowing down once he drew near to the plant, Ling Yun was able to see that the river had subsided and returned to its peaceful form. He only used the corner of his eye to sense the location of the Shichiyou Herb as he flew towards it without a reduction in speed. Other than a few splatters of mud on its leaves, the Shichiyou Herb was perfectly fine.