I see in all sidurim in nussach of retse (BHMZ of Shabbat) "לשבת בו ולנוח בו". But recently some books changed the nussach to "לשבות בו ולנוח בו"
So far I believed that the kamats in place of Cholam was right and I tried to understand. In Rashi Ytro I just discovered some thing similar (Shemot 19, 24):
וְהַכֹּֽהֲנִ֣ים וְהָעָ֗ם אַל-יֶֽהֶרְס֛וּ לַֽעֲלֹ֥ת אֶל-יְהוָֹ֖ה פֶּן-יִפְרָץ-בָּֽם:
Rashi: One Precision, Rashi calls "Melopum" what we call nowaday "Holam"
פן יפרץ בם. אף על פי שהוא נקוד חטף קמ"ץ, אינו זז מגזרתו, כך דרך כל תיבה שנקודתה מלאפו"ם, כשהיא באה במקף, משתנה הנקוד לחטף קמ"ץ:
despite that the "יפרץ" is ponctuated (under the letter Resh) "Chataf kamats", he do not change signification. This is the rule: All word which is ponctuated with Melopum when it precedes a "Makaf", the vowel changes to "Chataf Kakmats".
May be that Lishbot bo is "לשבת-בו" and all is resolved.
But apparently this is not obvious. Some books changed the nussach to "לשבות בו ולנוח בו". If someone understand clearly the rule, I will be grateful to learn from him.