The anonymous tipper asked the server to pay it forward, and to visit the website for the ReesSpecht Life Foundation.

The receipt with the $3,000 tip, and Richard Specht, the teacher who inspired it.
(via ReesSpect Life)

Paying a kindness forward can make a big difference.

In 2012, on the eve of Superstorm Sandy, Richard and Samantha Specht's only son, Richie (aka "Rees") drowned in a pool in their backyard due to a miscommunication with a neighbor about who was watching him. As they were dealing with that tragic accident, their community in Long Island surrounded them with support, including a local nursery that turned their pool into a garden in memory of Rees.

Touched by that kindness, Richard and Samantha created the ReesSpecht Life Foundation to help pay forward kindnesses to others in need. The foundation has awarded over $6,000 in scholarships to local students, and it promotes acts of kindness worldwide. One of the ways it does this is by providing cards that people can leave when performing acts of kindness, encouraging the next person to pay it forward as well. You can order the cards on online — they're free, but a donation to the foundation is encouraged. Over 100,000 cards have already been distributed.

Sources: h/t Distractify | ReesSpect Life