The following verse is from the book of Ecclesiastes:
Two are better than one, for they get a greater return on their labor. For should they fall, one can lift the other; but woe to him who is alone when he falls and there is no one to lift him! Also, if two sleep together they keep warm, but how can one be warm alone? Where one can be overpowered, two can resist attack: A three-ply cord is not easily severed!
Ecclesiastes 4: 9 – 12
טובים השנים מן האחד אשר יש להם שכר טוב בעמלם. כי אם יפלו האחד יקים את חברו ואילו האחד שיפול ואין שני להקימו.גם אם ישכבו שנים וחם להם ולאחד איך יחם.ואם יתקפו האחד השנים יעמדו נגדו והחוט המשלש לא במהרה ינתק.
קהלת ד ט – יב
This verse carries personal significance to me as applied to the debate (both my own internal debate and in the business world at large) of whether to go at a business venture solo or together with partners. I have found merits to both sides of the argument, and both paths surely contain many potential pitfalls. That said, I found the certitude of these verses in Kohelet to be quite convincing in the face of my own wavering: two are better than one.