to fast: to go without food for a time as an act of humbling oneself before God, in mourning, repentance, or urgent prayer
TranslatabilityApproximateCertaintySettled
To fast in the Bible is never a diet or a health routine. It is a deliberate turning of the whole person toward God, almost always in a hard moment: mourning the dead, pleading for a life, confessing sin, or begging for rescue. Going without food is the outward sign of an inward posture the Old Testament calls humbling or afflicting oneself (עָנָה), and it regularly travels with weeping, wearing rough sackcloth, and sitting in ashes.
The same act turns up across a range of settings that shade into one another:
a single person fasts in private grief or earnest prayer, as David did while his sick child lay dying
a whole community is summoned to fast together when disaster strikes or the nation needs to repent
fixed days of fasting are kept year after year to remember past calamities
The prophets warned that the act can go hollow. Isaiah pictures people fasting while they exploit their workers and quarrel, and God rejects it outright: the fast he wants is to feed the hungry and free the oppressed. So the word carries a built-in tension. It names a genuine expression of devotion, and also the very ritual most easily faked or emptied of meaning. The related noun (צוֹם) names the fast itself, the occasion or event, while this word names the doing of it.
always a turning to God in grief, repentance, or urgent prayer, not a neutral act of skipping food2Sa 12:16Neh 1:4
Both
both name a deliberate going without food for a set period of timeEst 4:16Jdg 20:26
Only fast
in everyday modern English "to fast" can simply mean following a dietary or health regimen (intermittent fasting), stripped of any grief, penitence, or reference to God
“fasted”
Comparison data is not available for this English gloss yet.
How tsum differs from similar Hebrew words
צוֹםthe noun from the same root: the fast itself, the occasion or the event, whereas this word is the verb, the act of fasting.
עָנָהto humble or afflict oneself; "afflicting the soul" is the standard description of what a fast accomplishes, but this word covers any self-denial or hardship, not only going without food.
names one concrete practice, going without food, taken up freely toward God in penitence or petition2Sa 12:16Est 4:16Neh 1:4
marks grief for the dead, when mourners abstain from food to honor the one they have lost1Sa 31:132Sa 1:121Ch 10:12
Both
both name self-denial practiced before God in penitence or appeal; Isaiah 58 sets "we have fasted" beside "we have afflicted our soul" as one and the same gestureIsa 58:3
Repeatedly a whole community's act in a national crisis: the people gather and go without food as one body facing defeat, siege, or threat.Jdg 20:261Sa 7:6Est 4:16
Accompanies grief and mourning for the dead, as when men go without food after burying the fallen.1Sa 31:132Sa 1:121Ch 10:12
Can become empty ritual that God rejects: the people go without food while oppressing others, and are told their fasting does not reach him.Isa 58:3Isa 58:4Zec 7:5
Both
Both name voluntary abstention from food as a religious act, and the Greek word is the standard New Testament term for the practice the Hebrew word names in the Old.1Sa 7:6Mat 4:2
Both pair going without food with earnest appeal to God, as a way of pressing a prayer or seeking his help.2Sa 12:16Neh 1:4Luk 5:35Act 13:3
Turns up in Jesus's warning against fasting to be seen: the practice must stay hidden, done for God rather than for a public reputation.Mat 6:16Mat 6:18
Becomes a point of comparison between religious groups: the disciples of John and the Pharisees fast, and people ask why Jesus's disciples do not.Mat 9:14Mrk 2:18Luk 5:33
Marks the early church setting apart leaders: fasting joins prayer as the community sends out and commissions people for God's work.Act 13:2Act 13:3
What scholars say about tsum
The lexica agree on a single sense with no live debate: HALOT and BDB gloss the verb as "to fast, abstain from food," the act expressing mourning, penitence, or petition. The verb is the base of the noun צוֹם (H6685) and is regularly bound up with the idiom "to afflict the soul" (ענה נפשׁ), with sackcloth and ashes, and with weeping and lament. Scholarship distinguishes the same overlapping settings visible with the noun: spontaneous individual fasting (2 Samuel 12:16, 21-23; 1 Kings 21:27;Nehemiah 1:4), proclaimed communal fasting in national emergency or repentance (Judges 20:26;1 Samuel 7:6;Ezra 8:23;Esther 4:16), fasting as a mourning rite for the dead (1 Samuel 31:13;2 Samuel 1:12;1 Chronicles 10:12), and the fixed calendrical fasts of the post-exilic period (Zechariah 7:5). The prophetic critique (Isaiah 58:3-4; Jeremiah 14:12) insists the practice is worthless when divorced from justice and genuine repentance.