यस्मात्yasmātind.From which, since, as.
यतो यतो निश्चरति मनश्चंचलमस्थिरम् ।
कोशःDictionaries
V. S. Apte, The Practical Sanskrit–English Dictionary. Look up any word of the Gita in Devanagari, IAST or Harvard-Kyoto, or browse the headwords letter by letter.