$ crontab -l
# run user's script every day at 23:00 and save output as logfile; 
# make sure, /var/log/user_script.log is writable or use different path; e.g. /home/user/log/user_script.log
# the directory for the log file must exist!
0 23 * * * /home/user/bin/script >/var/log/user_script.log 2>&1

# or you simply don't care about the output
30 23 * * * /home/user/bin/script >/dev/null 2>&1