Exegesis:

eukopōteron de estin ton ouranon kai tēn gēn parelthein ‘but it is easier for heaven and earth to pass away.’ de ‘but’ implies a contrast with v. 16, and suggests probably that the new situation to which v. 16 refers does not imply that the law is no longer valid. parerchomai means here ‘to come to an end,’ ‘to disappear.’

ē tou nomou mian keraian pesein lit. ‘than that one hook of the law falls down.’ tou nomou is emphatic by position.

keraia lit. ‘hook’ as part of a letter, i.e. some insignificant part, dot, stroke, comma.

piptō lit. ‘to fall,’ here ‘to become invalid.’

Translation:

For easier cf. 5.23; for heaven and earth see 10.21.

To pass away, or, ‘to be destroyed,’ ‘to go to ruin,’ ‘to die’ (used metaphorically), ‘to become dead, as it were’ (as simile), ‘to cease to exist.’

Dot. The rendering should preferably be the name of a small item in the script best known in the culture, cf. e.g. “dotting of an i” (An American Translation), “comma” (The Four Gospels – a New Translation), ‘period’ (Thai 1967, Fulah), ‘tilde’ (Tzeltal), ‘dash,’ indicating a vowel (in Arabic script, Zarma), ‘dot,’ indicating the ng (in Balinese script). Other versions use a descriptive rendering, e.g. ‘part of a letter’ (Kituba), ‘tiniest word’ (Ekari), ‘small (thing) written’ (Lomwe), ‘small mark’ (Pohnpeian), “smallest detail” (Good News Translation); cf. also, ‘were it only something very small (lit. like the dirt in a nail)’ (Toraja-Sa’dan).

Quoted with permission from Reiling, J. and Swellengrebel, J.L. A Handbook on the Gospel of Luke. (UBS Handbook Series). New York: UBS, 1971. For this and other handbooks for translators see here . Make sure to also consult the Handbook on the Gospel of Mark for parallel or similar verses.