There are no tax implications for your father-in-law giving you and your wife a cash gift beyond filing a gift tax return (Form 709) with the IRS.
See https://www.irs.gov/instructions/i709#en_US_2022_publink16784xd0e314
Note that there is an annual exclusion of $17,000 (per person/donee) for the 2023 calendar year which means he could give you and your wife up to $34,000 without having to file a gift tax return.
See https://www.irs.gov/instructions/i709#en_US_2022_publink16784xd0e649
Also note that your father-in-law will not actually pay any gift tax unless he exceeds his lifetime exemption, which is currently $12.92 million.
