Farmers generally know the source of good seeds. They define "good seeds" as seeds that have not been genetically modified, that yield a robust harvest, and that are naturally resistant to insects and diseases. Spiritually, a good seed is one that yields only that harvest which we personally would welcome into our lives. If the expected harvest is something we would not want for ourselves, then its seeds always should be rejected.
In the realm of the spirit, whatever seeds we plant always return to us a harvest, even when we are not the intended recipient. The 60/40 rule in physics describes an energy principle which dictates that 40 percent of every harvest from the seeds we plant always will return to us, whether or not we intended a harvest for ourselves. Thus, when we pray for others, we also should expect that 40% of the harvest from the seeds of that prayer always will return to us.
Doing good deeds is one way of planting "good seeds", as is thinking beneficial, positive thoughts, and speaking positive, uplifting words. Essentially, everything that we do for others or do to others always returns to us a 40% harvest in keeping with the nature of the seed. When we think or speak to or about others with strong emotion, those thoughts and words also abide by the 60/40 rule. If you know that you would reject the harvest from the seeds of your thoughts, words, and actions, don't plant the seeds.