I believe his reference could be related to the Shabbath, the day of rest. And, I believe he could have a belief that is understood according to the reality of the past and to the current times. In other words, it is known to other people that we try to keep a holy day for rest and peace which is done in a certain manner. That being said, it's a "good day" for a potential enemy to disrupt the rest. So, people who are trying to have sleep and rest on this holy day, are and have been targeted by people who know about "the rest" and the rules for keeping it holy. Military tactics. There is no peace as we are always waiting on the enemy to be without rest because history has proven this time best for the enemy to attack. That is my understanding about this. Also, when you live around people in a culture that does not keep the day of rest, or the people around you keep it in vain, it's a metaphysical hell for any person trying to rest according to God's ways..and this disturbs the energy of any mystic. I can't rest, there is no peace because the surrounding energies are always in opposition to my energy. I'm familiar with this way. Yeah, I know of no peace or any rest on God's day of rest. Sleep is not allowed. It's a day of distress for me because I want to keep God's ways in the way I was instructed ..but there is no harmony with "other energies", I mean from others who live around me. True story. We, the mystics, usually will do the best we can to observe this time but it's a weekly affliction day to many. There really are more reasons but these two are more popular to understand what he means. Concerning the desert, I cannot say anything for certain but this seems like a mystical connection about much. I sense a connection about the past and the way of mystery.