Today I received a notification that XYZ has accepted my friend request. I do not know the person and do not remember sending any request to him.
Is there any way to check if I sent the request to him or not?
You can now go to the friend requests page at https://www.facebook.com/friends/requests/ and select "View Sent Requests" which will take you to this page https://www.facebook.com/friends/requests/?fcref=ff&outgoing=1.
This should give you a list of friend requests you sent.
Even though Facebook seems to have closed the "Pending friends" API, Here is an app that you can use. I myself tried and it works.
I found a loophole to see pending friend requests on Facebook Timeline. Although Facebook does show you with all the friend requests received, there is no direct means to access the request you have sent from your account. But you can still keep track of them using the Facebook’s “Download Your Information” option. Follow:
You're done! c:
For detailed tutorial with screenshots, visit:http://www.sociobits.org/2013/04/view-your-pending-friend-requests-on-facebook-timeline-may-2013.html
Just click this link to get your list of outgoing Friend Requests.
You can install a script such as Unfriend Finder to track activities regarding friend requests. It will also notify you when someone ignores your request, remove from you from his/her friend list, activate/deactivate his/her facebook account. Pretty handy.