Sample letters of sympathy are at websites YourDictionary, Quick Condolence and WriteExpress. Some of the samples use general language for anyone who has suffered the loss of a loved one; others are specific to the loss of a child, a parent or a friend.
Sample condolence letters can help people to express sympathy when they have difficulty finding the right words on their own. Some have formal language for those who are acquainted with the grieving person but not close. Other letters are more informal for close friends and relatives to let those who are grieving know they are not alone. Some may use religious words and phrases; others may have secular language.