Player notes: Sain teamed with Warren Spahn to form a great 1-2 pitching punch during his years with the Braves. The tandem was immortalized by the phrase "Spahn and Sain and pray for rain."

According to the Baseball Almanac, the original doggerel was written by
Gerald V. Hern of the Boston Post and published on September 14, 1948
in his column.
First we'll use Spahn
then we'll use Sain
Then an off day
followed by rain
Back will come Spahn
followed by Sain
And followed
we hope
by two days of rain.
(Thanks to Paul Konstadt for this information)

Sain led the league in many pitching categories in 1948, and finished second in the MVP balloting. Once he went to the Yankees he was used more in relief than as a starter, and led the AL in saves in 1954 with 22. He was known as a great control pitcher. He was a twenty-game winner four times with the Braves, with the 24 wins in 1948 being his career high.

Sain went on to be a highly-respected pitching coach during the 60s and 70s. Sain passed away in Chicago on November 7, 2006.

According to Carl Moore:

I remember reading that the "pray for rain" saying came about because Spahn and Sain started two consecutive games. Then there were several days of rain, enabling the Braves to use those same two pitchers in that team's first two games after resumption of play.