Sam felt like this oath thing is a bit over the top.
But after hearing this guy's story, he understood what exactly is happening. This guy is so in love that he is so afraid that he would be losing the opportunity to reach her sooner all the while fearing that the opportunity that came to him is a hoax.
Sam didn't have enough patience to convince him normally and since the tree spirit oath is active he doesn't have to bother too much about the future situation.
After the whole narration is completed, they both pledged that the contents they spoke here wouldn't be revealed to another person and that is exactly what happened.
While walking back to the town, Sam is currently thinking about what kind of luck he had. He is attracting lovebirds once again. Previously in Naga Loka, he encountered the two Yaksha who are so in love that they tried to kill him to keep the secret.