You can lead a horse to water....

...but you can't make it drink (1st.extra.) Alternatively, if you prefer the Old English version from 1175 " Hwa is thet mei thet hors wettrien the him self nule drinken."
As a saying, it has lasted pretty well.
Seen on our spin this morning. The rider did a great job of handling two horses, especially in a river, whilst using a cell 'phone.