Did Martin Luther believe in guardian angels?

In some traditions, the concept of "guardian angels" is often looked upon with suspicion. While there might be agreement that angels (generally speaking) protect people (generally speaking), the idea that each individual has an assigned guardian angel for life is met with skepticism. Such an approach is found in Calvin, for example: > The words of Christ do not mean that a single angel is continually occupied with this or the other person; and such an idea is inconsistent with the whole doctrine of Scripture, which declares that the angels encamp around (Psalm 34:7) the godly, and that not one angel only, but many, have been commissioned to guard every one of the faithful. ([commentary on Matthew 18:10](https://www.ccel.org/ccel/calvin/calcom32.ii.lix.html)) However, in contrast to Calvin and other later reformers, Martin Luther often had a closer affinity to the beliefs of Catholicism ([which does accept the idea of guardian angels](https://christianity.stackexchange.com/a/25107/21576)) . Thus I'm curious – **did Martin Luther believe in guardian angels?** Naturally we'll want to limit this to his post-1517 writings. But given the amount of evolution in his views on many subjects, great answers will include sources from different periods in his life, not just a single piece of evidence.