Shloka – Bhagavad Gita – Chapter 16 – 23,24

यः शास्त्रविधिमुत्सृज्य वर्तते कामकारतः ।
न स सिद्धिमवाप्नोति न सुखं न परां गतिम् ॥१६- २३॥

तस्माच्छास्त्रं प्रमाणं ते कार्याकार्यव्यवस्थितौ ।
ज्ञात्वा शास्त्रविधानोक्तं कर्म कर्तुमिहार्हसि ॥१६- २४॥

One who rejects methods or wisdom of Shashtra and behaves and acts according to his own wishes, that person doesn’t achieve success, nor does he attain the highest path, nor does he gets happiness. – 16-23

Hence for you, Shashtra is the proof and evidence on what to do and what not to do. Knowing the importance of shastra, you should act according what is defined by Shastra. – 16-24