The phrase "a vow that" is correct and usable in written English.
You can use it when referring to a promise or commitment made, often in a formal or serious context.
Example: "She made a vow that she would always support her friends in times of need."
Alternatives: "a promise that" or "a commitment that".
The two renewed a vow that Muci made in the concentration camp.
In 1997, after Princess Diana's death, the third Viscount Rothermere promised that the paper would no longer use photographs taken by paparazzi — a vow that didn't last.
It is a vow that is made explicitly by Arthur during "The Sherlockian" but is honored in this book by Mr. Moore too.
She vows to help her father find evidence proving Mr. Harvey's guilt, a vow that will put her directly in the serial murderer's path.
They had to swear an oath of secrecy that they now also impose on Herter, a vow that must remain in effect until their deaths.
And so, each year, on Nov. 11 — the day of the armistice that stilled the guns in 1918 — the poppies renew a vow that also came to embrace the dead of World War II.
Some Democrats are saying the White House set itself up for the charges by making a vow that was bound to be difficult to keep and that would risk alienating its business supporters.
Adolphe had once told his son that if anyone killed Mbonimpa, the general would avenge him with his own hand – a vow that gave Mbonimpa courage to continue with his campaigning work.
The MP made a vow that suggests future UK military interventions will become rarer: "Let us say we will never again unnecessarily put our troops under fire and our country's standing in the world at risk.
Her lawyers claimed a vow that Soulsbury made in 1993 to give her the money when he died in return for stopping maintenance payments of £12,000 a year was not legally binding.
