From Stuka! - Joachim Dressel:
In the fuselage of the fourth prototype Ha 137V4, D-IFOE, a Jumo 210 A-1 engine of 610hp was fitted by Blohm & Voss. Colonel von Richthofen proposed producing the Ha 137 in large quantities, but Ernst Udet, who became the Generalluftzeugmeister and was responsible for all kinds of development of new aircraft for the Luftwaffe, decided to cancel the Blohm & Voss aircraft even though the flight behaviour was very good and the conversions showed an improved armament consisting of two 20mm cannon and two MG 17.
From Ju-87 Stuka - Robert Jackson:
Powered by the 610-hp Jumo 2I0Aa, the new aircraft were the Ha 137V-4 (D-IFOE) and V-5 (D-IUXU). The radial-engined and in-line engined versions were respectively designated Ha 137A and Ha 137B, the latter being the proposed production version. The Ha 137 was designed around a wing based on a single strong tubular spar which also served as the fuel tank. It was tough and maneuverable, and a certain amount of surprise was expressed in some quarters when it lost out to the Ju 87. The decision, however, had political undertones, as the Blohm and Voss concern was originally of Jewish origin.
From JUNKERS Ju-87 Stuka - Peter Smith:
The first round of tests began in May. Both the Ar 81 and the smaller Ha 137 were eliminated early in the contest, despite the fact that Udet, as Director of Air Armament, favoured the former and von Richthofen, Chief of the Technische Amt, the latter. Udet's choice was influenced by the fact that the Arado was a biplane...
...
On 9 June 1936 von Richthofen, adamant as ever, ordered the cessation of all further work on the Ju 87, but on 10 June he was undermined by the appoint-ment of Udet himself to the command of. the Technical Office, whereupon the lat-ter immediately reversed this decision. In his new position Udet could now press the dive-bombing idea, and adopted brainchild, to the limit.