In Jain dharm according to most household (shravak) rules:

• Masoor (red lentil) / masoor dal is generally allowed as a pulse/daal.
• It should be:

- Old/dry grain (not fresh, not sprouted) - Cleaned and checked for insects - Cooked fresh the same day

• During Paryushan, Ayambil, Chaturmas, special vows, many people:

- Either reduce pulses, or - Avoid masoor (and some other legumes) completely, depending on local maryada and guru’s instructions.

There is also difference in practice:

• Many Shwetambar families eat masoor dal in normal days.
• Many Digambar families are stricter with legumes and may avoid masoor regularly.

So:

• For ordinary Jain vegetarian diet: masoor is usually permitted.
• For you personally: follow your family/guru/local sangh maryada. If your elders say “don’t eat masoor”, then you should avoid it.