unthankful

not feeling or showing gratitude; "ungrateful heirs"; "How sharper than a serpents tooth it is / To have a thankless child!"- Shakespeare

विनष्ट हुआ मनुष्य! कैसा अकृतज्ञ है!

And whosoever does deeds of righteousness, being a believer, no unthankfulness shall befall his endeavour; We Ourselves write it down for him.