In The Name of Allaah, The Most Merciful, The Bestower of Mercy.
“The invitation of two people who compete each other should neither be accepted nor should their food be eaten”.
Shaikh Zaid [rahimahulaah] said, “If invitation to eat food is done for boasting, self-importance and show off, do not respond to the invitation. Competition related food is to boast about its abundance and perfect preparation- everyone wants to give more than the other. Whoever competes in [providing] food and its preparation – each of one of them invites others to come along and eat his food, then do not accept their invitation because they have not done so sincerely for the sake of Allaah due to the competition and boating in the affair. And this is something impermissible.
[At-taleeqaat Al-Maleehah Alaa Silsilah al-Ahaadeeth As-Saheehah. Vol 1. Page 396. Slightly paraphrased]