cash from father

Gift received under a Will or by way of inheritance is fully exempt in the hand of legal heirs.
This money is fully exempt in your hand as it will cover in exception of section 56 (taxability of gifts)

No penalty on this sum will impose by income-tax department.

sir actually after death of my father I came to know by my mother that cash amount we have... so I put that cash in to my saving account... but I don't have any proof to show... my father was railway pensioner..

You can also show it a gift from your mother which is also tax free. No documentary proof required of gift received from relatives. But for safer side, it would be better to make a gift deed.

i differ with mr. sunil. in order to prove it as genuine gift, you need to prove the credit worthiness of the donor I.e. father or mother.. if it's liquid cash, definitely your father should've withdrawn the same from his bank account. if you can corroborate cash withdrawals with the amount of cash deposits then there won't be any problem otherwise it'll be deemed as your income for the concerned previous year