Sentence:  This is the harmony, this is the resurrection of a Christian, in this respect, that his soul be always so fixed upon God, as that he do nothing but with relation to his glory principally, and habitually; that he think of God, at all times, but that, besides that, he <WSD>sepose</WSD> sometimes, to think of nothing but God: that he pray continually, so far, as to say nothing, to wish nothing, that he would not be content God should hear, but that, besides that, he <WSD>sepose</WSD> certain fixed times for private prayer in his chamber, and for public prayer in the congregation. 
Meaning of the word marked with <WSD> tags:  To set apart.