Wa `alaykum As-Salamu waRahmatullahi wa Barakatuh.

No Muslim should utter such words or expressions. The cow is holy only for some Hindus; for others, it is simply a creature of Allah. To worship cow as a mother is a pagan concept; so by uttering such words, we are condoning or reinforcing such superstitious beliefs and practices.

Those who speak such words should seek repentance; for in Islam shirk or associating partners with Allah is the ultimate sin; so we can never take this lightly.

Allah says: “God does not forgive idolatry, but forgives anything else for whomever He wills. And whoever associates anything with God has concocted a monstrous wrong.” (An-Nisaa’ 4:48)

Almighty Allah knows best.