Shen Wei and the others had been in the Sacred Ruins Abyss for a long time. It had also been a long while since they had first discovered traces of Ling Tian and his companions. To their disappointment, they had not only failed to capture them, but had fallen farther and farther behind until they eventually lost their trail. They realized that it was nearly impossible to catch up with Ling Tian and the others, let alone capture them, relying on their own strength alone.
If they could not capture Ling Tian and his companions, they naturally could not seize the World-Ending Thunder Dragon. The Sacred Heart Sect was determined to obtain it, and that was why Shen Wei and the others had kept searching despite knowing they could not catch up.
Of course, they knew that their current strength was no longer enough to capture Ling Tian and his companions and claim the World-Ending Thunder Dragon. That left them with only two options. The first was to give up the pursuit and return to the sect, but they immediately ruled that out. The Sacred Heart Sect's cultivators were determined to obtain the World-Ending Thunder Dragon; they could not give up now. That left only one option: seek help from powerful members of their sect.
It made sense. In Shen Wei and the others' eyes, they were only a hair's breadth from catching up with Ling Tian and his companions. Their sect had no shortage of cultivators whose realms and strength surpassed theirs. Their master, for example, had already advanced to the Twenty-eighth Heaven of Near-Saint. They believed a cultivator at that level would certainly catch up with Ling Tian and the others once their whereabouts were discovered. And once he caught up, capturing them would be a simple matter.