Answer

No, not by itself.

Explanation

In strict Digambar Jain understanding, the main issue is attachment and possessiveness, not this sentence alone.

• Saying “my mother will always be in my heart” is an expression of love and remembrance.
• It is not a sin in itself.
• But the deeper Jain ideal is to reduce mamatva — the feeling of “mine” and possessive attachment.

So, if you want the strictest answer:

• The sentence is not a sin.
• The inner attachment behind it is what Jainism asks you to purify.

Spiritual Understanding

Jain Dharma teaches us to love with respect and compassion, but without clinging. Love for mother is natural, but the soul should move toward detachment, purity, and non-possessiveness.

Takeaway

No — it is not a sin. But in Jainism, the higher spiritual attitude is to love without “mine-ness.”