Canto 3 -
Araṇya-kāṇḍa
Chapter 9: Sītā Requests Rāma to Give up His Weapons
Text 3.9.31

आत्मानं नियमैस्तैस्तैः कर्शयित्वा प्रयत्नतः।
प्राप्यते निपुणैर्धर्मो न सुखाल्लभ्यते सुखम्॥

ātmānaṁ niyamais tais taiḥ karśayitvā prayatnataḥ
prāpyate nipuṇair dharmo na sukhāl labhyate sukham

ātmānam = their bodies; niyamaiḥ = [scriptural] restrictions; taiḥ taiḥ = through specific; karśayitvā = who make emaciated; prayatnataḥ = with endeavor; prāpyate = is attained; nipuṇaiḥ = by experts; dharmaḥ = piety; na sukhāt labhyate = cannot be obtained from sensual pleasure; sukham = sensual pleasure.

Piety is attained with endeavor by experts who make their bodies emaciated through specific [scriptural] restrictions.1 Sensual pleasure cannot be obtained from sensual pleasure.2

नित्यं शुचिमतिः सौम्य चर धर्मं तपोवने।
सर्वं हि विदितं तुभ्यं त्रैलोक्यमपि तत्त्वतः॥

nityaṁ śuci-matiḥ saumya cara dharmaṁ tapo-vane
sarvaṁ hi viditaṁ tubhyaṁ trailokyam api tattvataḥ

1 In other words, piety (dharma) cannot be attained by indulging in sensual delight (kāma).

2 Sensual pleasure in the next life cannot be attained by sensual pleasure in this life.