The two most popular Irish sayings are "May the road rise to meet you" and "Slainte." Both phrases are from Irish Gaelic and are traditional greetings.
"May the road rise to meet you" is a benediction that wishes another person success. It comes from the Gaelic "Go n-éiri an bóthar leat." "Slainte" can be roughly translated as "health."
Although "Top of the morning to you" and "The rest of the day to yourself" are believed to come from Ireland, they are not traditional Irish sayings. Both of these sayings gained popularity through American television and movies and are not derived from Gaelic.