Here in the printer’s manuscript, Oliver Cowdery initially wrote “listened to my word”, but then later the plural s was inserted with heavier ink flow. The s appears to be Oliver’s; he may have supplied it when he proofed 𝓟 against 𝓞, although editing is also a possibility given that the immediately following clause uses the plural pronoun they to refer to Gideon’s words. The surrounding text also uses the plural words in reference to Gideon’s advice to king Limhi:
verse 3 thou hast hitherto hearkened unto my words many times
verse 4 I desire that thou wouldst listen to my words at this time
verse 9 the king hearkened unto the words of Gideon
The use of the plural words is most probably the reading of the original text for Mosiah 22:4: “if thou hast hitherto listened to my words in any degree”.
In general, the text prefers the plural words when referring to the speech of humans. When referring to the word(s) of deity, the text has a considerable number of examples of both singular word and plural words. For discussion regarding “my word(s)”, see under 1 Nephi 16:24.
Summary: Maintain in Mosiah 22:4 the corrected reading with the plural words: “if thou hast hitherto listened to my words in any degree”.