Patanjali Yoga Sutra 2.1
Tapah, Svadhyaya, Isvarapranidhanani Kriyayogah.
A burning zeal in practice, study of spiritual books, self study and surrender to God constitute yoga.
Patanjali Yoga Sutra 2.36.
Being firmly established in truthfullness ones actions cannot go wrong.
Patanjali Yoga Sutra 1.1
Now the exposition of Yoga begins.