Which detail is given in the chapter about "posture the arms are" in Pranayama And Kriyas?
Yogic practices of asana, pranayama and meditation relax body and mind.
Even small things may make them angry.
But at the same time, he does not want to be seen as a spoilsport by his friends.
In this posture, the arms are stretched upwards, hence is called Hastottanasana.