There's a word in the text of psalm 61:8 that Michael Fishbane (Biblical Interpretation in Ancient Israel) suggests is a scribal acronym about the spelling of preserve. The transcription made me laugh as I tried to express it in translation.
[Full spelling v8 (Fishbane p 61) מַן min = מָלֵא נן male nun] Here the scribal comment on spelling has become part of the received text!
יֵשֵׁב עוֹלָם לִפְנֵי אֱלֹהִים
חֶסֶד וֶאֱמֶת מַן יִנְצְרֻהוּ
|8||yéshéb `volam lipnéy )elohym|
xsed ve)emet màn yincruhvu
|he will dwell ever before the face of God|
mercy and truth [note the full spelling] will preserve him