I took me quite some time to learn the introductory chant used before iyengar classes.
Here are some videos to help you memorize them.
The first one might not be as accurate as the following one by BKS Iyengar (further below) but it includes the words for those who need to see it written.
And here is another one with written translations of the invocation to Patanjali:
And finally, the same chant by BKS Iyengar himself: