Old English hem "a border," especially of cloth or a garment, from Proto-Germanic *hamjam (cf. Old Norse hemja "to bridle, curb," Swedish hämma "to stop, restrain," Old Frisian hemma "to hinder," Middle Dutch, German hemmen "to hem in, stop, hinder"), from PIE *kem- "to compress." Apparently the same root yielded Old English hamm, common in place names (where it means "enclosure, land hemmed in by water or high ground, land in a river bend"). In Middle English, hem also was a symbol of pride or ostentation.
If þei wer þe first þat schuld puplysch þese grete myracles of her mayster, men myth sey of hem, as Crist ded of þe Pharisees, þat þei magnified her owne hemmys. [John Capgrave, "Life of Saint Gilbert of Sempringham," 1451]
late 15c., probably imitative of the sound of clearing the throat. Hem and haw first recorded 1786, from haw "hesitation" (1630s; see haw (v.)); hem and hawk attested from 1570s.
late 14c., "to provide (something) with a border or fringe" (surname Hemmer attested from c.1300), from hem (n.). Related: Hemmed; hemming. The phrase hem in "shut in, confine," first recorded 1530s.
To hesitate; tergiversate; temporize: Stop hemming and hawing and do something (1580+)
of a garment, the fringe of a garment. The Jews attached much importance to these, because of the regulations in Num. 15:38, 39. These borders or fringes were in process of time enlarged so as to attract special notice (Matt. 23:5). The hem of Christ's garment touched (9:20; 14:36; Luke 8:44).