The gravedigger is singing songs while digging people's graves. Act 5 Scene 1 Line 67- 70 Hamlet - " Has this fellow no feelings of his business? He sings in grave making Horatio - " Custom hath made it in him a property of easiness. "
Hamlet is going to sword fight with Laertes an Horatio thinks he's going to loose. Act 5 Scene 2 Line 222-225 Horatio - " You will loose, my lord " Hamlet - " I do not think so. Since he went into France, I have been in continual practice... "
The King put poison in a cup for Hamlet to drink but the Queen drank it instead. Act 5 Scene 2 Line 317-318 King - " Gertrude, do not drink. " Queen - " I will, my lord ; I pray you pardon me. "