In his youth. The thought of this verse reminds us of Psalms 119:71. Youth is mentioned as the time when it is easier to adapt one's self to circumstances, and when discipline is most readily accepted.
The words do not prove that the writer is young, any more than Psalms 119:9 and Psalms 119:100 of Psalms 119:1-176. prove that the psalmist was an aged man (against this view, see Psalms 119:84-87). There is no occasion, therefore, for the textual alteration (for as such I cannot help regarding it), "from his youth," found in some Hebrew manuscripts in Theodotion, in the Aldine edition of the Septuagint, and in the Vulgate.
The reading was probably dictated by the unconscious endeavour to prop up the theory of Jeremiah's authorship. The scribes and translators remembered, inopportunely, that the trials of Jeremiah began in early manhood.