Removing a splinter from a parent:<a href="#_ftn1" name="_ftnref1">[1]</a>
It is [Rabbinically<a href="#_ftn2" name="_ftnref2">[2]</a>] forbidden for a son to remove a splinter that is stuck within the skin of his father [or mother] due to that one may come to cause him a wound in the process.
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<a href="#_ftnref1" name="_ftn1">[1]</a> Michaber 241:3; Rambam Mamrim 5:7; Sanhedrin 84b
<a href="#_ftnref2" name="_ftn2">[2]</a> See Sanhedrin 84b; Ran ibid; Sheilasos Mishpatim; Beis Yosef

Shulchan Aruch HaRav | Removing a splinter from a parent:

Removing a splinter from a parent:[1] It is [Rabbinically[2]] forbidden for a son to remove a splinter that is stuck within the skin of his father due to that one may come to cause him a wound in the process. _________________________ [1] Michaber 241:3; Rambam Mamrim 5:7; Sanhedrin