A dictionary of Proverbs (Oxford Paperback Reference)

TWO is company, but three is none
The alternative ending is three’s a crowd.

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  1706 J. STEVENS Spanish & English Diet. s.v. Compania, A Company consisting of three is worth nothing. It is the Spanish Opinion, who say that to keep a Secret three are too many, and to be Merry they are too few. 1860 T. C. HALIBURTON Season Ticket viii. Three is a very inconvenient limitation, constituting, according to an old adage, ‘no company’. 1869 W. C. HAZLITT English Proverbs 442 Two is company, but three is none. 1944 Modern Language Notes LIX. 517 Two’s company, three’s a crowd. 1979 J. LEASOR Love & Land Beyond viii. Two’s company and three’s none, so one of the three has been taken out of the game. 2002 Washington Post 10 Mar. SC11 (Family Circus comic strip) Two’s company, three’s a crowd. ‘’Specially on a tandem bike.’ "friends
  

TWO of a trade never agree

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  1630 DEKKER Second Part of Honest Whore II. 154 It is a common rule, and ‘tis most true, Two of one trade never loue. 1673 E. RAVENSCROFT Careless Lovers A2^V Two of a Trade can seldome agree. 1727 GAY Fables I. xxi. In every age and clime we see, Two of a trade can ne’er agree. 1887 G. MEREDITH Poems (1978) I. 148 Two of a trade, lass, never agree! Parson and Doctor!—don’t they love rarely, Fighting the devil in other men’s fields! 1914 ‘SAKI’ Beasts & Super-Beasts 96 The snorts and snarls.. went far to support the truth of the old saying that two of a trade never agree. 1981 E. LONGFORD Queen Mother vii. There is an old adage, ‘Two of a kind never agree.’ ■ quarrelsomeness; similarity and dissimilarity; trades and skills
  

If TWO ride on a horse, one must ride behind

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  1598-9 SHAKESPEARE Much Ado about Nothing III. v. 34 An two men ride of a horse, one must ride behind. c 1628 J. SMYTH Berkeley MSS (1885) III. 32 If two ride upon an horse one must sit behinde; meaninge, That in each contention one must take the [defeat]. 1874 G. J. WHYTE-MELVILLE Uncle John I. x. There is an old adage.. ‘When two ride on a horse, one must ride behind.’ 1942 V. RATH Posted for Murder VI. iii. There comes a point when you are very exasperating. .. ‘When two ride on one horse, one must ride behind.’ But I’m getting off for a while. 1986 A. CLARKE Mystery Lady (1988) iv. Collaboration on a book is an awkward business. If two people ride one horse, one of them must ride behind. ■ co-operation