Royals British Royal Family British Royal Family News Meghan Markle and Prince Harry Pay Tribute to Princess Diana on Instagram for the First Time "I think she would have been best friends with Meghan," Prince Harry said of his mother, Princess Diana, after his engagement By Erin Hill Erin Hill Erin Hill is the Senior Editor, Royals at PEOPLE. She has reported on Royals for the brand since 2015. Erin previously worked at PARADE Magazine and The Knot. People Editorial Guidelines Published on August 9, 2019 12:33PM EDT Meghan Markle and Prince Harry are continuing the legacy of Princess Diana. On their Instagram account on Friday, the royal couple shared an inspiring quote from Harry’s late mother, Princess Diana. “Carry out a random act of kindness, with no expectation of reward, safe in the knowledge that one day someone might do the same for you,” the quote read on a blue background that features Meghan and Harry’s joint monogram. In a caption, they wrote: “Words have the power to inspire, which is why we’re happy to share some of our favourite quotes. “From members of the public to public figures, from teachers and students to young leaders, we begin with a quote from Diana, Princess of Wales.” The inspiring post marks the first time that they’ve mentioned Princess Diana on their Instagram. However, they did include a touching nod to Diana in a photo they posted of baby Archie on Mother’s Day surrounded by Diana’s favorite flower, forget-me-nots. Alamy Prince Harry shared an exceedingly close bond with his late mother — and today, that bond continues with his mother’s family. Diana’s sisters, Lady Sarah McCorquodale, 64, and Lady Jane Fellowes, 62, feature prominently in the family portrait taken at Windsor Castle when Harry and Meghan celebrated the christening of their son, Archie Harrison, last month. See Every Photo That Exists of Baby Archie — from His Royal Arrival to His First 3 Months! “Harry is close to Diana’s family,” a royal source told PEOPLE. “It meant a lot to them to share a photo of their full family.” Sussex Royal/Instagram A family friend says the inclusion of the Spencers “is typical of both William and Harry to say in a very, very gentle way, ‘This is the family of our mother, and we want to reflect that.’ She is always in their hearts, but this is a public way of saying that she is still on their minds.” Diana’s sons have continued to keep her memory alive since her 1997 death, with Prince William naming his 4-year-old daughter Charlotte Elizabeth Diana. Harry and Meghan, meanwhile, shared how they plan to make sure Diana’s legacy lives on when they sat down for an interview after their engagement in 2017, with Harry saying he knew his mom would have loved his now-wife. “They’d be thick as thieves, without question,” he said. “I think she would be over the moon, jumping up and down, so excited for me. But I think she would have been best friends with Meghan.” Photo by Tim Graham/Getty Images To keep his mother “with us on this crazy journey together,” as Harry said, he proposed with a ring that includes two diamonds from Diana’s personal collection, as well as a stone from Botswana, where the two traveled early in their relationship (William proposed to Kate Middleton with Diana’s engagement ring in 2010). Can’t get enough of PEOPLE’s Royals coverage? Sign up for our newsletter to get the latest updates on Kate Middleton, Meghan Markle and more! Meghan noted that keeping Diana close to their hearts during their engagement was important to her too. “Not being able to meet his mom, it’s so important to me to know that she’s a part of this with us,” she said.