Determine weekend based on country I've a table called BOND which have columns BOND NAME, COUNTRY of ISSUE and ISSUE DATE

BOND  Country  ISSUE_DATE
===========================
B1    INDIA    20-AUG-2017
B2    ISRAEL   18-AUG-2017


How do I find the issue date is weekend or not based on the issue country of BOND, without changing NLS_TERRITORY

SELECT TO_CHAR(ISSUE_DATE,'DY') DAY FROM BOND;

In the above dates 18-AUG-2017 is a weekend in ISRAEL but not in INDIA
Try to test the following: 

select
TO_CHAR (issue_date, 'D', 'NLS_DATE_LANGUAGE=HINDI) IN (6, 7)
from table 


To see if it works for you. One thing you need to check is, depending on the country, if the week starts at a Monday or Sunday. You might have to change those in values accordingly.
Edit: doing this, you're only changing the value on the query. Isn't it what you wanted? And sorry for not getting the value right. Corrected.