A dictionary of Proverbs (Oxford Paperback Reference)

FULL cup, steady hand
Used especially to caution against spoiling a comfortable or otherwise enviable situation by careless action.

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  c 1025 Durham Proverbs (1956) 15 Swa fulre fet swa hit mann sceal fegror beran [the more full the cup, the more carefully must one carry it]. c 1325 Proverbs of Hending in Anglia (1881) IV. 293 When the coppe is follest, thenne ber hire feyrest. 1721 J. KELLY Scottish Proverbs 346 When the Cup’s full carry it even. When you have arrived at Power and Wealth, take a care of Insolence, Pride, and Oppression. 1889 C. M. YONGE in Monthly Packet Christmas 46 Poor things! They were so happy—so open- hearted. I did long to caution them. ‘Full cup, steady hand.’ 1903 G. H. KNIGHT
  

Master’s Questions xxi I would listen..to this question..whenever..I am eagerly reaching out my hands to grasp what may satisfy an unlikely ambition. All hands are not steady enough to carry a full cup. "good fortune; prudence
It’s ill speaking between a FULL man and a fasting
A hungry man is never on good terms with a well-fed man; in quot. 1824, used as an incitation to eat.

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  a 1641 D. FERGUSSON Scottish Proverbs (STS) no. 1349 Thair is nothing betuix a bursten body and a hungered. 1824 SCOTT Redgauntlet I. xi. Ye maun eat and drink, Steenie.. for we do little else here, and it’s ill speaking between a fou man and a fasting. 1934 J. BUCHAN Free Fishers ii. It’s ill speaking between a full man and a fasting, but two fasting men are worse at a crack. ■hunger; quarrelsomeness
  

Out of the FULLNESS of the heart the mouth speaks
With allusion to MATTHEW xii. 34 (AV) Out of the abundance of the heart the mouth speaketh.

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  c 1390 CHAUCER Parson’s Tale 1. 626 After the habundance of the herte speketh the mouth ful ofte. 1699 T. CHALKLEY Fruits of Divine Meditation in Works (1751) II. 26 Out of the Abundance of the Heart the Mouth speaketh. 1861 TROLLOPE Framley Parsonage II. x. As out of the full head the mouth speaks, so is the full heart more prone to speak at such periods of confidence as these. 1932 ‘S. FOWLER’ Hand-Print Mystery ii. The murder.. had been in the background of her mind all the time. ‘Out of the fullness of the heart the mouth speaketh.’ ■speech and silence