Here are some memorable quotes from Abraham Lincoln, thanks to the compilation by Farnam Street:
On Failure
The probability that we may fall in the struggle ought not to deter us from the support of a cause we believe to be just.
On the importance of hard work
Work Hard, Then Work Harder
The leading rule for the lawyer, as for the man of every other calling, is diligence. Leave nothing for tomorrow which can be done today. Never let your correspondence fall behind. Whatever price of business you have in hand, before stopping, do all the labor pertaining to it which can then be done.
On Belief In Yourself
Always bear in mind that your own resolution to succeed is more important than any other one thing.
The most important attribute to have
On the whole, my impression is that mercy bears richer fruits than any other attribute.