Without more context I'd guess it referred to having a sound foundation for everything you do. Jesus is credited, in the Vulgate, with making a pun on the name "Peter": Tu es Petrus et super hunc petrum aedificabo ecclesiam meam. ("... upon this rock I will build my church"). I don't know whether this pun would have worked in Aramaic.
Of course, if you have a sound foundation for everything you do you are bound to have a clear conscience.
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