Just one day after Katy Perry dissed Britney Spears on the Grammys red carpet, the pop princess is speaking out.

Opening up to her 15 million fans on Instagram, Britney, 35, posted a photo of a sunset framed by a hand-made heart along with a very telling Bible verse.

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"Her mouth speaks from that which fills her heart. Luke 6:45," she captioned the post.

Fans applauded her decision to take the high road in the feud, with one commenting, "Don't let someone like Katy get you down @britneyspears. You are an amazing person, her comment was disgusting! I'm here for you."

A source also revealed that the mother-of-two was taken aback by the jab on the red carpet.

Britney thought it was hurtful. She doesn’t understand why Katy would take a jab at her," the insider told Hollywood Life. "There’s never been any bad blood between them. She thinks it was a low blow and not cool at all.”

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On Sunday night, Katy shaded the "Toxic" singer twice about her infamous breakdown when speaking about her decision to go blonde and her hiatus between albums.

"It’s like the last color in the spectrum (blonde). I’ve done all of ‘em," the 32-year-old told Nancy O'Dell. "The only thing left to do is shave my head which I’m really saving for a public breakdown. I’m down for that.”

katy perry britney spears getty

She later told Ryan Seacrest, "Well, that’s called taking care of my mental health… I haven’t shaved my head yet!”

This week marks the 10th anniversary of Britney's 2007 head-shaving incident, which may have prompted the backlash against Katy.

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Recently, Britney opened up about her troubled past and how she was feeling today.

"I like my 30s way more than my 20s,” she told Britain’s ITV. “My 20s were horrible! [Being] in my teens was fun, but I like my 30s.”

She continued, "I’m in a really good place right now. I’m loving myself every day and learning who I am. It’s awakening, it’s cool."

For a look back at the celebrity feuds of 2016, click through the gallery below!