You may get ideas from my post at the link

https://bbs.pinggu.org/thread-699918-1-1.html


%macro stringit(varlist);
  
  %let n= %eval(%sysfunc(countc(%cmpres(&varlist),%str( )))+ (%length(&varlist)>0) );
  %let varlist2=;

    %do i = 1 %to &n;
     %let cur_var=%str(%')%scan(&varlist,&i)%str(%');
     %if &i=1 %then %let varlist2=&varlist2 &cur_var;
     %else         %let varlist2=&varlist2 &cur_var;
   %end;
   
&varlist2
%mend;

%let VARS=
ABCD EFGH AAC BBD CCE 1 234 675  iab2
;

%put %quote(%stringit(&VARS));