abide v.

prefix or inseparable particle, a conglomerate of various Germanic and Latin elements.

In words derived from Old English, it commonly represents Old English an "on, in, into" (see on (prep.)), as in alive, above, asleep, aback, abroad, afoot, ashore, ahead, abed, aside, obsolete arank "in rank and file," etc., forming adjectives and adverbs from nouns, with the notion "in, at; engaged in." In this use it is identical to a (2).

It also can represent Middle English of (prep.) "off, from," as in anew, afresh, akin, abreast. Or it can be a reduced form of the Old English past participle prefix ge-, as in aware.

Or it can be the Old English intensive a-, originally ar- (cognate with German er- and probably implying originally "motion away from"), as in abide, arise, awake, ashamed, marking a verb as momentary, a single event. Such words sometimes were refashioned in early modern English as though the prefix were Latin (accursed, allay, affright are examples).

In words from Romanic languages, often it represents reduced forms of Latin ad "to, toward; for" (see ad-), or ab "from, away, off" (see ab-); both of which by about 7c. had been reduced to a in the ancestor of Old French. In a few cases it represents Latin ex.

[I]t naturally happened that all these a- prefixes were at length confusedly lumped together in idea, and the resultant a- looked upon as vaguely intensive, rhetorical, euphonic, or even archaic, and wholly otiose. [OED]

Middle English biden, from Old English bidan "to stay, continue, live, remain," also "to trust, rely," from Proto-Germanic *bidan "to await" (source also of Old Norse biða, Old Saxon bidan, Old Frisian bidia, Middle Dutch biden, Old High German bitan, Gothic beidan "to wait"), which is of uncertain origin. According to Watkins possibly from PIE root *bheidh- "to trust, confide, persuade" (via notion of "to await trustingly").

Frequent in Middle English (to bide on live was "stay alive;" bide in bay was "stand at bay"). It was preserved in Scotland and northern England, displaced elsewhere by abide in all senses except in the expression bide (one's) time.  "I Bide My Time" is said to be "the motto of the earls of Loudon" in a Scottish context [1806, in a note to "Poetical Words of Sir David Lyndsay"], and it may owe its popularity to Scott's significant use of it in "The Bride of Lammermoor":

Ravenswood, who had assumed the disguise of a sewer upon the occasion, answered, in a stern voice, "I bide my time;" and at the same moment a bull's head, the ancient symbol of death, was placed upon the table. The explosion of the conspiracy took place upon the signal, and the usurper and his followers were put to death.

Related: Bided; biding.