A video that captures the moments a Muslim woman was the subject of a racist verbal attack on a Sydney train has been viewed nearly 80,000 times.

The video was recorded on a phone by Stacey Eden, 23, who can be heard telling the older woman to stop disrespecting the Muslim woman who was with her husband and wearing a headscarf at the time.

Ms Eden, a pathology worker, told the ABC she was catching a train home to Mascot on the Airport Line at around 1:40pm on Wednesday afternoon.

She said she noticed a group of people enter the train, particularly a man and woman wearing a scarf with a baby.

At that point she said an old lady walked over and started speaking to them.

"I was just listening to my music," Ms Eden said.

"The old lady actually bent over and touched the lady's scarf while she was talking.

"I didn't think anything of it."

Verbal abuse made reference to Islamic State

Ms Eden said she noticed the old woman was verbally abusing the couple, who said nothing.

"The lady next to me was saying things like 'all the people that were dying were because of the Muslims in the world and look what's happening overseas'," she said.

Stacey Eden intervened on a Sydney train when a Muslim woman was verbally abused. ( Supplied: Facebook )

Ms Eden said the woman continued by saying: "Read the newspapers, why are you following this religion for, why do you wear things like that so you can marry a man who's going to go marry a 6-year-old?"

"I was like 'this isn't right, why are you saying these kinds of things?'"

In the video, Ms Eden can be heard telling the old woman to leave the other woman's dress alone.

"She wears it for herself, OK," she said in the video.

"She wears it because she wants to be modest with her body, not because of people like you who are going to sit there and disrespect her."

The older woman can be heard mentioning beheadings, the Sydney siege and suggesting the woman was an "ISIS supporter".

Ms Eden said she got angry and started recording the incident.

"She was picking on her for the way she was dressed and that's what really got to me," she said.

"This lady that was sitting across from me wearing a scarf, she was minding her own business, she never said anything out of line, she never even spoke.

"That's why I decided to say something because it just made me really angry and upset."

Police encourage victims of racial abuse to come forward

Ms Eden said she missed her Mascot stop to make sure the couple felt safe and once she saw them get off at the International Airport stop, she got off at Wolli Creek.

"I was actually worried about what was going to happen," she said.

"I stayed on the train for a few more stops just to make sure everything was going to be OK.

"As they got off they thanked me."

The victim's husband, Hafeez Ahmed Bhatti, posted a thank you message on Facebook which said: "This video was not made by me. That is what happened to us on a Sydney train, God bless Stacey Eden she supported us".

The husband of the woman who was verbally abused posted a thank you message on Facebook. ( Supplied: Facebook )

Ms Eden said she felt compelled to stand up because no one else was doing anything.

"I just felt like if no one said anything, it was just going to keep going, so I had to say it," she said.

"People like that are just very ignorant. They're never going to listen to what you say.

"I didn't want to cause an argument or have a confrontation, I just wanted her to stop talking just so she wouldn't keep making them feel bad about themselves."

A New South Wales police spokesman told the ABC they would review the video footage.

"NSW Police is aware of an incident which occurred on at train travelling on the Airport, Inner West and South line involving alleged racial vilification yesterday," a spokesman said.

"The Police Transport Command is reviewing a video posted online in an effort to identify the alleged offender."

Police said they had not received a report of the alleged assault and were encouraging the victims to come forward.

"We encourage anyone who is the victim of a biased motivated crime to report the matter to local police or Crime Stoppers on 1800 333 000," they said.

Race Discrimination Commissioner Dr Tim Soutphommasane from the Australian Human Rights Commission said the video was "inexcusable".

"It's always disappointing to see people being subjected to harassment or abuse in public places," he said.

"There's simply no excuse to be abusing people or to be harassing people because of their religious beliefs or their racial background."

Dr Soutphommasane said it was encouraging to see Ms Eden stand up to the discrimination.

"It's always encouraging to see people respond to racism or bigotry," he said.

"If it's safe to do so, people should feel free to speak out against abuse or harassment.

"By speaking up, we send a powerful message that we don't accept or condone bigotry and racism."