it's the end of the second chapter of Dao De Jing. I try to make sense: 是以不去 therefore it's not lost, doesn't go away. 夫唯弗居? Can anybody help me?
Nannuo gave a nice explanation. But there are some of the details I don't agree with.
It seems 夫 is 发语词 to me. Normally one doesn't relate it to anything.
夫唯弗居 => 唯弗居 => Only contributing without taking credit.
以 means "because of". 是以 = 以是 = because of it/this/the reason/something.
去 = leave （vanish is also good.)
是以不去 => 以是不去 => Because of the reason above, it (the credit of your contribution) never go away.
Apologies for my late reply.
I have no formal training in classical Chinese, modern-day Chinese or something akin thereunto; however, in a Japanese sense, the answer should be more or less clear.
My answer is thus shown as follows (in a tentatively explanatory note):
Someone in question is/was merely not at home; therefore, he is/was not gone ([or] he has/had not left for anywhere else [for good]).
The [...] thread has not provided the entire excerpt or, better still, the entire article/account; therefore, I have no choice but to deem that, from these given words, the author of the original phrase ([or] the first-person character or any of the likes) seems to have responded to his or her listener(s)/reader(s), or seems to have provided an explanatory note in re the perceived departure, i.e., as to whether or not someone in question be/have gone. The author has apparently made it clear that the person in question merely was not at home, as opposed to having gone somewhere else (for good [or not]).
Note: In my opinion, whether or not one choose (chooses) to treat the first character (meaning in general: man, husband, this, etc.) as insignificant when being translated into English, it does not matter. The meaning in its essence remains clear that someone is/was merely not at home for the time being; thus, having gone nowhere (as possibly expected/assumed thus or so).