一切經音義 63.7

63.7

若躡（下黏輒反廣雅云躡謂足所履也方言云登也蒼頡篇云蹀也說文蹈也從足聶聲聶音上同蹀音牒）。

If treading upon [若躡]: The second character (nian + zhe [niè]) is explained in the Guangya: 'Niè refers to what the feet tread upon.' The Fangyan states: 'To ascend.' The Cang Jie pian states: 'To step.' The Shuowen states: 'To tread; formed with "foot" [足] as radical and niè [聶] as phonetic.' 聶 has the same pronunciation as above; 蹀 is pronounced dié.