The light of Hassadim [mercies] cannot shine in a place that was restricted. It is like a person who engages all day long in idle things, and when he comes to pray, he wants to pray with intention. And yet, we see that he is given foreign thoughts and cannot aim his mind during the prayer. Although prayer is bestowal, meaning that his Kli is light of Hassadim, yet why does the light of Hassadim not shine for him then?
The reason is that the light of Hochma is attached to the light of Hassadim, since they are one light. If he is given light of Hassadim when all his Kelim [vessels] are immersed in reception, he will taste the Hochma [wisdom] that is found in the Hassadim, and it is impossible to separate the Hochma from the Hassadim.