We often hear the expression 'don't judge a book by its cover', which means we should not form opinions or a person by his or her outward appearance.

This incident at the Universiti Sains Malaysia's vaccination centre (PPV) in Penang yesterday, is a testament to that.

According to a post in the university's official Facebook page, an elderly man arrived at the centre in a taxi, looking rather bizarre - with a face mask, and plastic bag tied over his head.

"He sure did attract a crowd and we could hear whispers and sarcastic laughs from the public.

"Nonetheless, he proceeded till he got his jab," said the post.

However, what the "bizarre-looking" uncle did next came as a shocker to everyone at the venue.

"The frontliners have been working very hard. Please buy them lunch," the man reportedly said while handing a wad of cash to the staff at the vaccination centre."

Photos of the heartwarming incident was captured by staff photographer Baim Manan on the stop. For their part, health professionals at the venue also advised the uncle to remove the plastic covering over his head and gave him a face shield as a replacement, before he left in the same taxi he came in.

"Appreciate good people, they are hard to come by. He stunned us with his generosity and humanity.

"Dear uncle, God bless. Let us give him so love," read the post, which has gone viral over 8,200 likes and more than 2,500 shares since it was posted yesterday.

The uncle did put a lot of people who judge others by their appearance to shame. He has proven that one does not necessarily be beautiful outside, to be beautiful inside.

Photos source: USM Facebook