Is this not done and against the law?

In books it is about 50 years after the death of the author... The same might apply to song text, but I am not sure....

IMHO using that phrase might violate the copyright, and also not to violate. It is on the fine line in between. It would depend on many, many aspects.

You may risk it. If your track becomes hit, they will sue you almost for sure. If they would win, hard to say. But even if you change it a bit, it still might violate copyright.

If you do not expect your track would be hit, you might change the wording a bit. Also you may ask Bowie, or more specifically the author of the text.

I think you will be fine personally, there is a difference between using a few words spoken yourself and ripping the actual tune/sequence/sampling itself.

There are countless examples where a similar verse or even quoted lyrics in something like a diss track are used, the thing is you can't just fine someone without mounting a legal case, with costs and such, which maybe if the artist was making a mint off your actual work you could justify, but the fact you are asking on this forum suggests you do not have a legal adviser or production team to answer this, so chances are you are not hitting the million record sales so again, chances are what you make will not even reach the ears of anyone that would care about it (in the nicest way of saying). There would be more chance of the audience taking offence to the likening of the lyrics or feeling it's a cheesy piggyback on an artist who has passed.

If there was an issue, you may be initially requested to take down the material and remove the offending part more than direct legal action so really up to you if you feel that choice of lyrics would make your song better. If in doubt I would suggest consulting proper legal council or maybe just change it to mean the same thing but using a different approach... "We could be people that excel at our enigmatic tasks, just for 24 hours"

A agree with D-One.

I would add:

Generally, most people break many laws including copyright very often. It becomes almost impossible to live decently and not to break any law.... (It sort of reminds me of 'communistic times'. People had to break the laws every day and the system accepted it. Unless, they needed to get rid of that person. Than they came and said, you have broken law in this, this, this and this. Go to jail....)

So, legaly it might be violation of copyright to use part of the lyrics. But if yes or not depends on many, many things. I guess only very specialized lawyer in copyright could tell you. And he would not say for sure. Because it depends... In my experience most lawyers avoid the intellectual property law like the devil the cross. Because it is like swamp and more about feelings, emotions and uncertainity than pure facts.

You should be fine using it, althought IMHO there is tiny, small risk. But getting born brings continuous line of risks.