You can either use two single quote characters where a single quote is required, or define a constant who's value is character number 39. If you have many quotes to embed (this can happen in a complex SQL statement), the second method is preferred. Example:

const Quote = #39;
{This line will not compile!}
ShowMessage('The smith's yard is greener than ours');
{This line will compile}
ShowMessage('The smith''s yard is greener than ours');
{This line will compile}
ShowMessage('The smith' + Quote + 's yard is greener than ours');