Likutei Moharan Tinyono 11
Da kesheadam mitpalel basode, azai kol hoasavim kulam ba’in betoch hatfila, umisayin lo, venotnin lo koach betfilato. Veze bechinat shenikret hatfilo sicha. Rebbe Nachman says… I want you to know that when you pray in the field, every blade of grass comes and helps you, and gives you strength to pray. And, therefore, he says, prayer is called sicha. The little grass in the field is called siach hasadeh, and prayer is also called sicha. So, he says, prayer is actually called ‘little grass from the field.’
It says of Yitzchak, “Vayetze Yitzchak lesuach besade” [Isaac went out to pray in the field]. Or, to pray with the field. He went out in the field in order that all the grasses of the field should help him pray.
Therefore it says in Devarim [Deuteronomy], and we say it in the Shema, “Vehoadomo lo titen et yivula [If you deviate from G-d’s way, then the earth will not yield its produce].” What does it mean? Rebbe Nachman says that it means that the earth will not join you when you pray. Because, he says, even if you are not exactly in the field, but since you need the field for your food, and everything comes from the field, regardless, the field is with you all the way, and helps you pray. Therefore, he says, ‘Yivul’ is the initials of Vayetzey Yitzchak Lasuach Basade. Meaning, the fruit of the field, ‘Yivul’ is made up of the same letters as ‘Yitzchak went out to pray in the field.’
(הדש’ב חוש’ל קחצ’י אצי’ו :תובית ישאר – “לובי” )