A very simple Jain line you can teach and repeat daily for good sanskār is:

“मेरे मन, वचन और काय से किसी भी जीव को दुःख न पहुँचे।” (Mere man, vachan aur kāy se kisī bhī jīv ko dukh na pahūnche.) Meaning: “By my mind, words and body, may no living being be hurt.”

If you want a very short, traditional line:

“अहिंसा परमोधर्मः।” Ahimsā paramo dharmaḥ. Meaning: “Non‑violence is the supreme religion.”

Saying this daily, and trying to live it (kindness, truth, no hurting anyone) gives the best Jain sanskār to children and to ourselves.